I guess there is nothing can be done by forum moderators also they don't have privileges to change the authors of the threads. Also such requests will be ignored by administrators too, it very rare admins handle such cases.
Moderators can delete the threads but that is also after same valid reasons. There three moderators for Russian board:
LZ,
xandry,
Xal0lex. You can contact any of them on PM but with some more valid proofs, "thread discussion" won't be enough.
Btw I don't think account is hacked but I guess thread is changed intentionally, it is best if you contact the author "kovaleksandr" himsefl/herself. Only he/she can update the thread.