A lot of limitations in RealBand can be remedied with a few add-ons.

KV Element allows chaining midi vsti, using Vst3, plugins that won't work in RealBand normally, advanced routing, allows all vst windows to be opened at the same time...

12 Channel Mixer

reastream.dll VST from https://www.reaper.fm/reaplugs/ will give you midi&audio sends/receives and allows track FX changes,
see video: RB-FX-Sends.mp4 a fader can be added in front of the FX chain to give master volume.
*Note to use a track as a receive put an empty clip on the track or a small 1 bar empty audio clip at the end of the track this will activate the FX.
Fader VSTs
ReaTrak Biab & Plugin in Reaper
Free Biab Chord Picker Tool