If you end up needing to go with a new derailleur you should look at a Shimano CX-70. Although it is marketed as a "ultegra quality" double, it has the range to handle three chainrings and it will certainly clear a 42T or 44T middle ring. Here's a discussion by Jan Heine where he recommends that derailleur for his Rene Herse triples:
https://janheine.wordpress.com/2013/...h-sti-triples/