Plugin with bug fixes for SoD.

What logic did the author follow?

The author's (Baratorcha's) logic was, firstly, that the map editor's tooltip for the Naga Bank states that it provides dragon stones, and secondly, that each resource bank (except the Naga Bank) provides the resource associated with the city whose creatures defend the resource bank.

As for the logic of the author of this plugin (that is, me), it is as follows:
1) It is impossible to prove that sulfur in Naga Banks is a bug - it was not fixed by NWC (although this was obvious, it was impossible not to know about it). That is, this is the original mechanic that the authors of the classic Heroes 3 maps had in mind (and still have).
2) Resource balance in the game. Gems can be obtained on maps in the Enchanted Garden, and not just once, as in the Naga Bank, but every 2 weeks. At the same time, there are probably more Enchanted Garden-type objects on maps on average than Naga Banks.
Another interesting point related to resource balance is that sulfur is significantly in demand by 5 factions in Heroes 3, while gems are in demand by 3 factions. In addition, in terms of the total amount required for buildings, gems are the least in demand among resources.

These points related to balance were taken into account by NWC. That is, this is generally the elementary thing that some current modders and bug fixers cannot understand.