Registering an unregistered land title with the LR is relatively straightforward and takes perhaps a month. The current owner will have to make an application before any transfer can take place (i.e. land sale to another buyer). Complications may arise if the quality of the original deed or deeds are poor in terms of the land area described by the deeds, and hence the LR cannot 'map' the area well in relation to other parcels of registered land around it.
The walled area is more problematic. The application process to the LR is similar, but the proprietor has to provide evidence to the LR of a number of aspects, including that factual possession of the land has existed for a long enough period of time (at least 12 years). The evidence is typically in the form of sworn statements, plus any other documentation that may exist. The LR will then make enquiries that could involve writing to neighbouring landowners to see if any objection is made. It may also involve inspecting the site. In a way that it is good that it has a hard perimeter around it (the wall) as there can't be any dispute about where the physical boundary to the land is. 6 months perhaps - your guess is as good as mine.
Bizarre that the property has even been offered for sale without first sorting this out.