Versions:

Minecraft 1.12.2
Impact 4.9.1
mixinbootstrap 1.1.0

when I try to start mining for example uranium ore from the Industrial Craft 2 mod, it gives an error "error at Argument #1: expected forBlockOptionalmeta". I tried various ways to start mining, but everything led to the same result.

Is it even possible to automatically mine resources from various other mods?

the structure is #mine modname:blockname
my guess for industrial craft would be but this can be wrong. if you press f3+h you get advanced tooltips. hover over a item to see its full name. #mine ic2:uranium_ore

Might be that ic2 uses a generic ic2:ore (or similar) block and uses the meta value to distinguish the different ores. In that case you can use modname:blockname:meta (meta is a number from 0 to 15 inclusive and you'd have to try which one is correct) or you can use modname:blockname[property=value] (property is anything listed below the block id in the f3 debug screen when looking at the block).