This is the best way to do it within Unreal, and you will not be able to do much more before a long time.
The audio revamp will take a long time and although it will make the integration of effects such as timestretcher etc. easier in the future, it’s safer not to count on Epic for it - after all, they’re developing an engine first.
However there are better options: timestretching/granular synthesis-based effects are probably the best available technology now, implemented in AudioGaming AudioMotors or Crankcase Rev for instance.
Obviously realtime filters are available in both sound engines you mentioned, as well as meters (some are better than others).
All that being said you can already have nice results by modifying the pitch, as long as your base recordings are good and you spend some time tweaking your pitch system; for meters you can also use the Orban meter. Not much yet for real-time filters although coding such a plugin should become really easy now.
Considering your main objective for now is to learn I would first exhaust all possibilities offered by UE4; this will help you later, if you move on to audio midlewares, to better appreciate and master those.