Hey,
i have been tweaking a lot, and finally found a solution that solved my problem. I changed the line width from 0.35 to 0.3 and now I don't have these problems anymore. The print looks really fine. What also helped was the change of "z-hop when retracted" from 2 mm to 4 mm. These travel moves, which caused the entire problem, do not occure anymore.
I guess the whole problem was, that my 1 mm diagonal lines did not allow 3 full 0.35 mm walls to be printed. So the printer tried to fill space, where walls do not fit. I solved it only by passing by this problem with printing thinner lines. What happily works. Its more or less a work around, i think.
I have saved my printing profile now for that this does not happen anymore in the future.
The whole thing helped a lot to get more into 3dprinting.
Now i only have some PVA doesnt always perfectly stick in the first layer problem, so that the rest of the print would be ruined and i have to watch in the beginning.
I sometimes catch and hold back the big pva blob before its moved around by sticking with the printing core and from time to time i get the message, that print cores do exceed realistic values. After some leveling it worked, and i am ok with the results, not knowing where i could improve much more right now.
Thank you gr5, for your help.