Well I guess you should deal with cromwells same as you deal with t34/85s, 2 paks is standard call, if stugs get flanked use spotting scopes on them and p4 shouldn't go alone, it's important that you support every unit with what you got, tellers don't have to be everywhere sometimes it's enough to put it on choke point and later or sooner it will drive over it. If you are getting overwhelmed by tanks it would be a smart choice not to split over the map and focus on one part and watch your flanks.
Unfortunately, spotting scopes, stugs, and double paks, just don't work on maps like dussledorf. That was specifically the type of map I was referring to. On other maps I have to problem with dealing with tanks of all types.
The next question I guess is how you deal with Calliopes as ostheer in a 2v2 AT where the USFs Ally actually helps defend his Calliopes for him? I had a game a few months back against Ciez and Momo and they went Calli and crom spam with arty cover on rails and metal. I went Jaeger armor and got 222 with spotting scopes for my elephant and a pwerfer. They just kept bombing us out they rushing with croms. Felt pretty hopeless...