ruudygh screenshots? to better be able to narrow down where the problem may lie
like what kind of collision problem?... maybe try upping the substeps and/or the point collision attributes on the zSolver; but even then still would need images/videos for more details as this may just highlight what the problem might be if it's not already obvious
(but as far as i know, i don't believe there is a collision weight map or collision stiffness weight map... however, you can also adjust zMaterial settings or even add zMaterial layers for localized control on problem areas, and play with the properties--as they can impact how a tissue may interact with itself)
(even providing an image of your rig, as joint placement can play a factor as well, again hard to tell without more visual info)
there's also a thread on subtissues, that could directly apply to this, that JamesJ & AndyVS gave feedback on:
https://community.zivadynamics.com/d/421-cartoon-character-tissue/3