No, RPG in a Box is a standalone project made with Godot, created in the same way that a game would be made.
It won't be increasing in the short term, however I may potentially look into increasing the limit in the future. This would most likely come after the upgrade to Godot 4.0, during which I will be taking the opportunity to rework and optimize the Voxel Editor to better handle higher voxel counts.
I wanted to create a simple language that could be tightly integrated into RPG in a Box. As Bauxite is still being developed, it will be continually growing to add more functionality and capabilities. At this time I don't have any plans to support other languages. It's similar to some other languages, like Lua, and is very easy to pick up if you have knowledge of basic programming concepts.
Yes! You are free to distribute and sell your games, with no strings attached (i.e. no royalties, licensing, or fees). Although it isn't required, crediting the use of RPG in a Box is always very much appreciated!
No, I don't currently have any plans for it to be open source.