Sascha with "c", but its ok ;-).
I have trilaminate, Santi as well, which I use in combination.
Unfortunately i have only drysuit experience in this combination, so no experience with Halo or Weezle or Kwark or ... you name it.
I have not washed it, and I use a base layer to avoid that as much as possible.
Shop and instructionsheet says best is washing by hand "Handwäsche" and less than 40°C.
I personally would stretch the washing interval as long as possible. Every undergarnment will loose isolation properties over time and probably a bit more if washed.(especiall improperly). So it has a limited lifetime.
I would also use a special soap for this material, which I would have to look up.