My organization uses Hamilton CapTel for TTY with the forking happening on the phone, and then we use recording via forking on the CUBE for PSTN calls. That does not solve internal-to-internal TTY+recording scenarios, but is one possibility for you.
I am not aware that CUCM can dual-fork, and I'm interested to hear if that is a possibility. Hopefully another engineer can chime in on this.
Maren