Be careful which BB3&4 you use. I’ve always used BB3&4 made in 2018 due to issues with newer Bb3&4.
As for 3.2. I’m using 3.2.2 ROMs (47.111) and 3.2.2.1 OS. From what I was told. 3.2.2.1 has a bug with the “echo” command.
3.9 is a good shout, but it is a very heavy OS and it will not have updated stuff like 3.2. Try and use PFs3 filesystem if you can.