To answer your question, yes you CAN use Timed mode with 50ms with just about any preamp/tape/filter/etc library.
The real question is SHOULD you.
I've got my opinions on this, but they are just my opinions. Try out Timed mode for yourself. You should hear the difference in the transients, and you can decide for yourself which is the best option for you. Do also keep in mind that the developers sell these libraries with Freqd as default for a reason too.
Like lots of other things in audio, it's subjective.