Feel free to join us during contributor meeting or on our dev chat on matrix.
We can discuss about this things, but as Aleks explained we have not a lot of knowledge on rspamd.
Maybe some topics on this forum could be helpfull to (don’t know i didn’t read it 
Comment améliorer la détection des spams (configuration rspam)?
Questions sur rspamd
Rspamd, filter and mail
And on issue Tracker:
[rspamd + clamav] add antivirus in the core! · Issue #1459 · YunoHost/issues · GitHub
[dovecot] spam mailbox is not created · Issue #1456 · YunoHost/issues · GitHub