It appears from their repo that they have 5-6 people working full time on this. Assuming about 250k per developer that puts their burn at 6 * 250k = 1.5 million a year. So yeah they have some time. Although I would be severely concerned at their progress considering it’s already been a year and they don’t seem to have shipped much. No proof of PMF or any sort of revenue with over a third of their runway depleted should have them hustling to get on the boards.
If you're looking for evidence in the public repo, consider what's not in there: one co-founder is missing, and so are the commits from the other author/co-founder for over a year. Not the signals you want in a dev-tooling project.
Except how many users do they have? If I were a VC fund looking to give them another round, I’d want to know their metrics, whether that’s users, downloads, or revenue. Judging by their blog, it’s been a year since they raised the money. Have they produced anything other than a bunch of code? Because code isn’t worth much without users.
Based on the release notes, the Typescript team is working on faster type-checking as continuous goal and has many big long-term irons in that fire. Though a lot of the more recent work has gotten into the performance of projects already scaled into project references and incremental builds, so it may not yet be obvious how much work has gone into performance if you consider your projects small/medium-sized.
It can sometimes be quite an effort to refactor a medium sized project into project references with incremental builds and there's currently no obvious moment where Typescript knows to tell you "you've got a 'large' project now, if you split this workspace into multiple tsconfig projects that smartly reference each other and switched to incremental build flags you'd get a bunch of performance improvements". So that's still a matter of figuring it out for your own projects if you can take advantage of that (and how you would take advantage of that).
[1]: https://trpc.io/