The Govt. of A.P has notified through G.O.Ms.No: 863, dated 20.06.2007 and introduced Act 19 of 2007, which amends Sec 22(A) of the Registration Act 1908.
 The C&IG (R&S) issued certain guidelines vide circular Memo No: G1/19131/05, dated 14.09.2007
 22(A)(1)(a) : Relating to Assigned lands
 22(A)(1)(b) : Relating to Lands owned by Government
 22(A)(1)(c) : Relating to Endowments /Waks lands
 22(A)(1)(d) : Relating to Surplus Lands
 22(A)(1)(e) : Relating to lands having interest of Central or State Government

 The C&IG (R&S) instructed if any deletions/ modifications to the lists already furnished by the concerned authorities should be communicated by the District Collector to the C&IG (R&S) for onward communication to the D.R for deletion / modification in the CARD prohibitory Masters.
 All the lists furnished by the concerned authorities shall be filed in a separate new file book titled as intimations / notifications of prohibited properties under Sec 22(A) and also publish such details in CARD.
 All the Registering Officers shall reconcile all the prohibited property data with concerned authorities once in a quarter and the report shall be submitted to DIG without fail.

The C&IG (R&S) directed vide circular Memo No: X1/4563/2010, dated 25.03.2010 that if any Registering Officer registers any prohibited property and it is proved in the enquiry, then the disciplinary authority shall normally impose a major penalty of dismissal from service.
 The Principal Secretary to Govt. in D.O letter no 359/Regn- I/2011, dated 01.04.2011 specifically clarified that except for properties related to Sec 22(A)(1)(e), no notification is necessary and the list furnished by the concerned authorities to the such registration to prevent registration is good enough.

The C&IG (R&S) vide Memo No: G1/15370/2012, Dated 27.07.2012 rescinded/ Withdrawn all the instructions, which were issued to insist for NOC from the revenue authorities before registration of prohibited properties.

The C&IG (R&S) vide Memo No: G1/15370/2012, Dated 27.07.2012 rescinded/ Withdrawn all the instructions, which were issued to insist for NOC from the revenue authorities before registration of prohibited properties.

1. Registration of Deeds by SRO (for prohibited /barred properties) do not confer any liability on SRO or any right /claim by property owner.  This is only a Title-Deed. Nothing else.

2. Govt., on persistent representations, do grant /generate special schemes for such unauthorized layouts and regularize them via heavy penalty and other parameters.  Technically there is no risk in such properties, since adverse disputes can be raised in Civil Courts and matters prolonged endlessly. 

The HC in this case held that Refusal to receive or take up a document presented for registration amounts to abdication of functions assigned to the Registration Department under the Act.

(3) The Act strikes at the documents, but not at the transactions. Mere act of registration on legal maxim nemo dat quod non habet does not transfer or create a right in favour of a party than what the vendor or executant possesses.

hence registration can be done by sub registrar office 

1.  There is nothing to assume and neither the Court judgement would stand in way of a subsequent Govt. Resolution to regularize any such unauthorized layouts.  The State Govt. is absolutely vested with discretionary powers, to do so.

Perhaps that particular section has been repealed subsequently hence the SRO if permitting registration of properties coming under that locality.

You may enquire from the authorities concerned about it and get clarified if you are interested in buying any proeprty from the list.

 22-A. Refusal to register certain documents .—Notwithstanding anything contained
in this Act, the registering officer shall refuse to register any of the following documents,
namely:—
(1) instrument relating to the transfer of immovable properties by way of sale, gift,
mortgage, exchange or lease,—
(i) belonging to the State Government or the local authority or Chennai
Metropolitan Development Authority established under section 9-A of the Tamil Nadu
Town and Country Planning Act, 1971;
(ii) belonging to, or given or endowed for the purpose of, any religious institution
to which the Tamil Nadu Hindu Religious and Charitable Endowments Act, 1959
is applicable;
(iii) donated for Bhoodan Yagna and vested in the Tamil Nadu State Bhoodan
Yagna Board established under section 3 of the Tamil Nadu Bhoodan Yagna Act, 1958; or (iv) of Wakfs which are under the superintendence of the Tamil Nadu Wakf
Board established under the Wakf Act, 1995,
unless a sanction in this regard issued by the competent authority as provided under the
relevant Act or in the absence of any such authority, an authority so authorised by the State
Government for this purpose, is produced before the registering officer;
(2) instrument relating to the transfer of ownership of lands converted as house sites
without the permission for development of such land from planning authority concerned:
Provided that the house sites without such permission may be registered if it is
shown that the same house site has been previously registered as house site.
Explanation I.—For the purpose of this section ‘local authority’ means,—
(i) any Municipal Corporation constituted under any law for the time being
in force; or
(ii) a Municipal Council constituted under the Tamil Nadu District Municipalities
Act, 1920 ; or
(iii) a Panchayat Union Council or a Village Panchayat constituted under the
Tamil Nadu Panchayats Act, 1994 ; or
(iv) any other Municipal Corporation, that may be constituted under any law for
the time being in force.
Explanation II.—For the purpose of this section ‘planning authority’ means the
authority constituted under section 11 of, and includes the Chennai Metropolitan
Development Authority established under section 9-A of the Tamil Nadu Town and Country
Planning Act, 1971;
(3) instrument relating to cancellation of sale deeds without the consent of the person claiming under the said sale deed.”.

This step, that is the Notification of Sec-22 A on Oct 20, 2016, is an important milestone in the ongoing efforts to streamline Regularization  of Unapproved Layouts and Plots 

The above is just the sample of the provisions of law under section 22A of registration act.

No they can't be regularise later without the state govt policy

Registration of sale deed is separate thing and dose not mean regularization of it. SRO is just filling govt. bag from revenue generating from illegal registration.

Only buyer will suffer lose.

It can be regularized subject to submission of application along with sale deed executed prior to date of notification of the Rules and payment of prescribed fees and charges.

Section 22 a(1)(e) deals with land in which central or state govt have vested interest.

No the property cannot be regularized later without any policy of state govt.