An admin responded in a semi-similar thread and suggested getting in touch with the mod to offer to join the mod-team or transfer the community: https://lemmy.world/comment/923510

My guess, given that this mod is semi-active, is that admins would want to see:

1. Community members offer to join the mod-team or take-over that are ignored or rebuffed for some extended time period like a week or more. There's a bunch of unanswered at-mentions in this post, so that's a decent start.
2. Evidence that the mod guidelines at https://lemmy.world/post/424735 aren't being followed (which based on this thread I think the "enough mods" guideline isn't... plus there are no sidebar rules, so I think there's a case here).
3. Gather links to any posts/comment-threads that are suffering due to undermoderation, especially if instance rules at https://mastodon.world/about (yes, that's a mastodon link, the admin teams are the same and that's where they post them) are being broken and not handled.
4. If the mod takes any retaliatory action like harassing you in DMs or banning people participating in discussions like this from the community, definitely document that as well.
5. Crosspost this to https://lemmy.world/c/moderators with all the evidence above asking for an admin intervention.

If there's a decent paper trail of the mod not meeting mod guidelines, not enforcing instance rules, and not accepting help... I think that's the point at which they might possibly consider intervening more directly. For a semi-active mod, they probably want folks to make a concerted attempt to work it out one-on-one first.