So I've made a mod including
9 tweaked techs.
14 new techs
1 new unit
3 new govs
and a totally redone tech tree.
I can load it but if anyone walks into a hut bad things might happen.
1. Barbarian huts just says nothing here.
2. Gold huts work
3. Advance huts, CRASH!!
4. Unit huts, CRASH!!!
5. City huts work (unless there is a city beside it of course)
6. Settler huts work.
The tech tree might have one or more loops. For example: prerequisite for industrial revolution = railroad and prerequisite for railroad = industrial revolution.
That causes the system to crash. If you havent any such things then I don't know, sorry.