Generic solution.
This solution is not fair to everyone but could be fair to the mostly regulars. Balancing the sheet so that sum is zero is a non-trivial problem.
There will be some profit or loss. Which is natural.
Folks can select some symbolic festival for Orissa e.g. Ratha Yatra and sponsor it. Float also comes to mind since it generates lotta publicity for Oriya folks.

By doing this we could run out of the fund in few years and again back to square one taxing for all festival until we accumulate enough surplus to sponsor one or two events for free.

Assumed loophole: this solution is not fair to all the Ghosti's and all the folks. Could be fair to most of the regulars but may not be fair to most of the Goshtis. e.g. cyclically the sponsored Rath Yatra could be handled by the same group for all the time. As long as the stake golders of each Goshti understand the risk, this seems to be a go in my mind.