Obviously I know "jad" but I don't see any issue with calling venom "trucizna". Natural languages aren't C++ and you don't get compiler errors when you speak - to me, there is no issue calling both venoms and poison trucizna. Polish dictionary doesn't seem to contradict it either:
https://sjp.pwn.pl/slowniki/trucizna.html
The point is, both are correct(afaik) while in English venom and poison are definitely two different things.