My character was banned in the Help channel, without explaining the reason

Incidentally:

6. Please use the correct language when posting.

The default language for posting on the EVE Online forums is English. Please use English when posting as a courtesy to other forum users, unless the forum channel is specifically created for discussion in another language as part of our localized language specific sub-forums.

https://community.eveonline.com/support/policies/forum-moderation-policy-en/