Yes, that's our fault -- we were planning to include this feature in
the TT2.2 update, but ran out of time for it (and forgot to remove the
UI). We'll be getting this into the 2.3 update for sure -- we're
wrapping it up and should be submitting it for review within the next
week or so.
The "Export" on TT will work by allowing your private key contents to
be pasted into your active session (eg, into an editor). Then this can
be imported back into TT Pro using copy & paste. (Unfortunately,
there's no way for the TT and TTPro apps on the same phone to share
information more easily.)