I am not sure if the OSMF should even support local chapters in areas like community building or legal and financial matters.
I think it is important that local chapters form organically. In my eyes, the OSMF should start getting involved once a local group contacts the OSMF asking for support; under no circumstances should the OSMF somehow try to “generate” local chapters. (Same for community building; I don’t think anyone, neither the OSMF nor local chapters, should attempt to construct a community that would not grow by itself.)
Once a local group contacts the OSMF asking for support, the OSMF must be careful to ascertain that the group contacting OSMF does indeed encompass (or at least: endeavour to encompass) the full breadth of the community in the region; we have seen very close-knit groups (like a university department from the capital) or even for-profit entities applying for local chapter status in the hope of bolstering their own recognition but with limited regard for community members that did not happen to be part of that group.
This can be a painful process that can (and must, in some cases) lead to rejection, and the OSMF must not lower its standards just to “tick off” more countries with local chapters. If there isn’t a group yet that has what it takes to be a local chapter, then maybe in a couple of years.
I think that the creation of less-formal user groups is welcome but I don’t see the OSMF playing a role in that. If local users don’t find it in themselves to band together and use the OSMF-provided communications channels to set up a regular meeting or whatnot, then I don’t see why the OSMF should try to goad people to do something they wouldn’t otherwise do. In my eyes, that’s bound to fail.
I think that if at all possible, local chapters and the OSMF should keep their finances separate. I don’t want local chapters to be eligible for financial support from the OSMF, nor do I want local chapters to pay the OSMF money - in order to keep both independent. I fear that if the OSMF were taking money from larger local chapters, those chapters could gain undue influence, and if the OSMF were supporting smaller local chapters, that could provide an incentive to boldly start local chapters that don’t have a leg to stand on.
I don’t think that local knowledge and priorities should influence global OSMF strategy at all. Local knowledge and priorities should influence the map and OSMF should keep out of that. Local priorities could lead to a local chapter lobbying the local government to release imagery or data or carve out an exemption in some law or other; all these things rightfully belong in the realm of the local chapter and have nothing to do with global OSMF strategy. I am also worried that any formal involvement of local chapters in OSMF business would create some “democracy issues” where you’ll find yourself in endless discussion about whether a chapter representing a country with 10,000 mappers should have more or less influence than a chapter representing a country with 1,000.
The one thing I’m surprised about how little it happens is inter-local-chapter communications. I am pretty sure that many local chapters must face comparable issues and I think it would be worthwhile for local chapters to discuss among themselves their challenges and solutions they found. Maybe I just don’t see it but it seems to me that very little such communication is taking place. Even though each local chapter is contractually obliged to send a report to the OSMF every year, I’m not even aware of any combined “state of the local chapters” report - how big are they in terms of budget or maybe even employees, etc. – I am not sure though if this is something where the OSMF needs to do something or maybe this is just another one of those “if local chapters wanted to talk to each other, they could” things.
I think what is working well is the relatively ample breathing room the OSMF gives local chapters - the local chapter agreement has very few rules and the trademark policy is very lenient. Other organisations in a similar situation can sometimes be overreaching or even paranoid in their rules about branding.
I would suggest that, should you become a member of the OSMF board, you focus on OSMF board stuff and let local chapters be local chapters; I think there is more than enough board stuff that needs doing and the best thing you can do for local chapters and for the other board workload is to leave local chapters be 
I have prefixed most paragraphs here with an “I think” because I know full well that mine is not necessarily a majority opinion.