There is one thing about your message that I don't really agree with, but for the rest of the message, can't agree more.
The issue definitely doesn't come from the fact that the staff manager doesn't wish to split the team into sections and give everyone different tasks. That's not what the server needs right now, and neither does the staff team need it. What the team needs to do is stay together, like they are doing right now, and deal with everything that needs to be done together. Platforms like the Discord server and forums are very well moderated and they are not used by that many people daily to require special attention / a separate team to be dealing with them. There are indeed some issues with these platforms, but they are extremely small.
I forgot to add that those sub-teams would've worked better with larger teams. At small numbers and with too many roles, you can't divide the team into sub-teams that well. At larger numbers, you could have a forum mod hop onto the game on the fly if no one is around (hence the reason for at least being somewhat familiar with the game).
I agree with restructuring helper recruitment, but still the problem lies in the exploits of the current requirements. 100 posts can be easily made with "post-farming" (notice the quotations) by posting in forum games or unrelated posts such as posting without reading the thread. Again, posts don't necessarily dictate good forum activity. Same goes for reports: 50 successful reports doesn't necessarily dictate catching rulebreakers well due to false positives or out-of-context chat reports, but it at least shows some competence in identifying rule violations. Lastly, while 3 months serves as a screening against fake accounts, month activity of 3 months can be exploited by creating a forum account way before. Your solution of having a sub-forum gets rid of the 3 month requirement.
Bonus: the questions on the helper application don't ask enough detail from the applicant. This makes it really hard to tell who is good and who isn't on paper and that's possibly why too many got screened out on the application round. Two interviews minimum seems better for the application: first one for screening candidates after passing the application round and second one for the real offer.