I have at least 4 different copper blocks (Mariculture, TE4, RC and TiC) and 3 different tin blocks (TE4, RC and TiC). When I craft a copper/tin block it gives me the RC version (which can't be used to make bronze blocks).

Not sure what are you asking. The mod does not alter the base recipe of creating copper or tin blocks. It can use those blocks in an induction smelter to make Tinker's Alloy Blocks (which is the Thermal Foundation version of bronze).

If you want to convert those metal blocks to another form you can take a look at MineFactory Reloaded's Unifier.

I just want to be able to use non-TE4 copper/tin blocks for the bronze block recipe

You should be able to use other copper/tin blocks in the induction smelter. It works for me with Railcraft blocks.

Closing due to inactivity. If this is truly a bug in the mod let me know.