The original sale deed in favor of Bajaj was not executed by the developer in the year 1994, moreover the sale agreement was an unregistered document, hence Bajaj has no marketable title to sell the property to Israni.
If the second document was a tripartite agreement, though it has been registered by paying the stamp duty, it was not a proper sale deed in the name of Israni, therefore it can be deemed that Israni is not having a title deed to the property in his name hence he may be considered to not to have marketable title.
The third document is not a registered document hence the impact of a proper title deed in favor of Israni was not felt as adverse to his purchase by the buyer Dhameja.
It can be deemed that the sale deed in favor of Dhameja also invalid in the eyes of law because it is not by a registered sale deed.
The fourth document was registered but without the vendor having a proper marketable title this registered document cannot be considered as a legally valid sale deed document.
The purchaser Rao's application for loan may be rejected by bankers for want of proper title and link documents confirming title way down.
Though there seems no irregularity or fraud in the transactions, the technical defects may need to be rectified.
If Bajaj is available, he can be asked to seek for adjudication before the concerned registrar's office after which the subsequent transactions can be ratified.