I would like to suggest the implementation of a plugin that gives the possibility of a heigher buildlimit. This would give builders a little more room to work with. I started my island at Y level 200, which was a big mistake. I now have verry little room to make large buildings.
The increasing build height isn't possible to implement even with a plugin, you may have a island already but there is a /movebedrock command to set your Y level.
I very much support this suggestion... if only it was possible. : ( After building my island's main terraforming I followed along with placing grass, trees, decor, etc but to my disappointment, I had accidentally built my island too high to allow for anything to be built at the top of the main mountain. If The height was raised this would mean a bit more freedom for myself in terms of building and for other players who have made the same mistake as me. I'm not really aware of any way of making this happen but yea... Hope there is some sort of solution!