Digital If I am reading this correct, that you cannot create a discussion with more then one primary tag, I believe @jordanjay29 is incorrect here (see image). Also, the same applies to secondary tags, they are not limitless to the secondary tags available but are restricted to the number the admin chose.
On the software level anyways, if talking about this site (discuss.flarum.org) it can configured to those parameters.

Eldenroot As Digital notes in your other thread, this (and the spam/flood question) can freely be investigated by you in Devflarum