As most Bhpian's have suggested, there is very little you can do legally here. Only way you can stall/ delay the process is get some influential people involved, but know this that it may come back to haunt you too.
Also, since you are away from India you may be overthinking things here, even if its going to cause a problem, you won't be living in the house anyway!! Do not spoil your sleep over things. As you have mentioned that you would like to retain the property for sentimental reasons, look for a trusted friend or a relative who can move-in and maintain the property for you. As someone mentioned earlier, if the house in abandoned it will surely cause alot of issues. Then you will be in a worse situation, as you can't do anything yet will be losing sleep over imagining what is going on back in India.
Lastly, there is no way someone is building a study library on a private land!! Its definitely a commercial complex, assume the worse and device a long term plan for this.
Best of luck.
Completely OT, sharing my personal experience in property dispute.
My father had applied for govt. land development scheme in the 80's and was allocated a residential plot far away from the city. Since he was in a transferable job, we moved around cities and lived in rented houses until I started working. Cut to 2012, this locality had fully developed and post my fathers’ retirement we wanted to build house with his lifetime savings and rest as loan which I was eligible for back then. Does the story sound familiar? Khosla ka ghosla, anyone. This is the south Indian version of it.
When the plot was allotted the lane was largely empty with few houses in-between. End to End the lane would have approximately 20~25 houses. Over ~30 years all the plots where built up except three. Our plot being the one in-between the other two owned by 2 different people. My father used to visit the plot once a month after watching Khosla ka ghosla movie, he was worried we will lose our plot too, thanks to that he made acquaintances of the neighbors in the locality. When the owner of the plot next to us decided to build a house he called my father to take some advice and invited him over when his architect was coming in for the recce and measurements. Fortunately my father visited the area and the first thing the architect mentioned was that if we total these plots they look smaller than actual. It was a passing comment and to prove himself right, he measured the three plots. Lo behold, it was short by 10 feet in width.
Now where did the 10 feet go was the question. He measured few of the immediate neighbors and found most of the house measure more than 30 feet i.e. 30.3, 30.5 and rarely 31 feet too. End result was we were short of 10 feet put together. This lead to a typically discussion over tea and biscuits at the “senior” member of the area’s house. No one was aware who the owner of the third plot was and the only possible solution was for the three remaining plots to take the hit equally. While my father and the one neighbor were ok with this, we needed the third person to also agree to this. No one knew who he was and when we found out who he was, as luck would have it, he turned out to be a property dealer who had bought this land few years ago with a sole intention of reselling it for profit. No prize for guessing, he out rightly rejected the idea and asked us to take a hit of 5 feet each and not dare encroach on his land. It went on for about a month or so. Luckily for us my father’s close friends include lawyers, judges and local MP’s. One message from them solved the issue for us else there was no way we could have resolved the issue.
We built the house within the next 2 years to avoid an future issues and my parents have been living there since then.
THE END