RTF is a global modification that replaces all towns in the game.

I'll take a look... so, is it possible that the editor simply merges nearby points? Points that are very close to each other? Well, not merges, but collapses them?

I think that it's the triangles that disappear. As far as I remember, one of the units ported from Heroes 7 had one triangle missing on the helmet, in the eye slit.