Cool that it works better now. Well I usually like to cut away all the bass and the low mid / part of the center mid and split up channels like that, when it comes to troublesome synths eating the bottom away. Its nice to get some more control over messy sounds. Multi-band compression etc works good also, you can try to add a multi-band compressor to the synth also and go from there.

There are no solid rules I think more helpfull hints and tips when it comes to music. Personally I never really boost any bass at all, I mostly remove instead. I like to tidy up not needed frequencies from other sounds instead to make the bottom region work better.