Comments
I'd guess that there are some low-hanging fruit research projects that could help lots of organisations and individuals trying to maximise their positive impact across multiple cause areas (not confident on this because there are some groups whose work I am unfamiliar with).
Examples of existing research that fits this category are the recent post on "Ingredients for creating disruptive research teams" and Open Philanthropy Project's research on the history of philanthropy.
It's possible that having a small organisation explicitly focused on these sort of opportunities could be worthwhile. Otherwise, if someone tried more thoroughly list and prioritise projects, individuals could potentially work on this (and get funding through EA Grants?)
It seems like much of what the Global Priorities Institute proposes in their research agenda falls into this category, under the general label of "cause prioritization" rather than "meta-research on how to make progress on causes". This area may still be neglected in absolute terms, but it seems like one of the areas most esteemed and valued within the EA community. Personally, I would, however, like to see more meta-research of the kind you describe focused on questions like whether the Importance, Tractability, Neglectedness Framework works well as a heuristic for selecting causes where activity is cost-effective and more generally on the psychological influences (e.g. cognitive biases and framing effects) on the cause prioritisation judgements that EAs and others make in practice, but that seems more a question of what meta-research would be valuable rather than whether more of it should take place.