I'd go further than that. IRV doesn't work well for the application at all. To top it off, the fact that the curator finds running votes to be "exhausting" means the situation is biased towards inertia.
Every proposal that gets seconded by two or three or four other participants should simply be the object of a binary vote where the two options would be "implement proposal" and "don't implement proposal". (The proposal can be a mix of things, of course. So if you want A + B + C and only want them if they're together, you suggest voting on it, if four others agree, then a binary vote takes place between "implement A + B + C" and "no changes".)
Elegant, simple, and perfectly functional.
(I'd raise the support for a call for a vote to four instead of two because anything that has any chance of passing should have no problem at all getting the support of four people; raising the bar there has the effect of reducing the likelihood of a proposal that won't pass of reaching the formal voting stage, which would be an useless exercise.)