Thanks for reporting this, and thanks for taking time to work on it.
It is my pleasure. :-)
I found the source of the original bug you reported. I'll push a new release with the fix, when I get the chance, within the next week.
As for your other mods, I can take a look, but I have little time to maintain Aris as it is. I'm grateful that you're doing work on it, but I can't maintain an additional build system, and I have no desire to move away from GNU Autotools at this time.
No problem. I can take care of this (to maintain both build systems, no problem), at least in my fork.
In the meantime I fixed another problem:
Also, it seems that not all UTF8 characters are allowed in the formulas. This can be a problem when writing comments in different languages than English.
Copy-paste with Shift-Delete and Shift-Insert works unless you have special characters in the copied text. Of course, Ctrl-G and Ctrl-I works as announced.