Large tilesets are fixed in the two menus you mentioned:
Unfortunately I didn't account for such large tile-sizes being used. The core issue is tilekit not being designed to work with tile-sizes this large, that is, even if these menus were fixed the experience of using 128x128 tiles in tilekit will likely leave something to be desired. Ideally the fix is to sort out the core issue which is more of a substantial change than fixing those particular menus; this will require some thought on my part.
Thanks for reporting the issue!