There is already a lot presented here, so I won't repeat what has been said.
At a quick glance it seems to me that you have experts and a leader with management skills/ideas. That is good, but it is incomplete.
You are the pragmatic one: make their lives easier.
There are at least two areas you can cover:
- delving deep into the technical details of the language the startup elected
- improve the quality of the code, and smooth the rough corners of working with it
Those guys are experts in their fields, and this is good, but it does not mean that they know how to code their way out of a paper bag. Honestly, I have seen very bright people writing horrid unmaintenable code.
You have the opportunity to become the technical lead here. Learn the language inside/out, until you know all its subtleties. Learn the idioms the community use. Research the useful libraries that exist out there.
There are ungrateful, but useful tasks:
- who maintains the code source repository ?
- who writes/maintains the tests ?
- who monitors that the test-suite pass ? and identifies the guilty commits ? and ping the offenders relentlessly ?
There are some steps that help, whether very formal or not:
- how do you review the commits ? (is there an ownership associated with some areas of the code ?)
- how do you plan the work/tasks ?
There is a lot of peripheral activities around having ideas and writing code.
You have the opportunity to become the quality lead here. Learn the industry best practices (bit of "Agile", bit of scrum, bit of TDD, ...), and compose a process that fit your company. Learn build systems (make, cmake, ninja, whatever), and write the scripts that make building/deploying easy. Check on Jenkins (or whatever) and build a continuous integration server.
They are impressive in their respective domains and that is great. Since at the moment you are non-specialized, I would say it's time for you to identify the weaknesses (you may ask for their opinions too) and fill a(the) gap(s)!