I believe that is actually the OP's problem: originally, he only had a fear - and now someone who has "something to do with roofs" has also confirmed to him that it is justified.
Hello, what did you end up doing then? I now have the same problem and am not sure what to do. The wood at the recesses is partially so rotten that it is no longer load-bearing. I am afraid that it will eventually collapse... but I am not sure to what extent the rafters have a load-bearing function.