I had a pretty terrible experience at that job - no engineering manager, never had any code reviewed, hardly any collaboration with other team members so I was basically stabbing away in the dark trying to get my shit together in TS.
It took me far longer than a few hours to feel comfortable, probably more like over a month of coding to get to the point where I mostly understood how to express what I wanted with the type system, and had stopped doing C# things in TS and adhering to style guidelines - functional modules, types instead of classes, injecting dependencies etc. And another month or two? to really figure out how everyone has been (ab)using the type system to do more complex stuff.
After years and years in C# I spent half a year writing Typescript full time.
IMO it's not that Typescript is limited at all, it's just that the type system is different, more complex and also more flexible - there are typically more ways to define types compared to Java/C#, so a lot more decision points trying to write something elegant, or even just idiomatic/understandable, so IMO the learning curve is steep. And then you get to the fun stuff with more abstract type definitions, infer keyword...
It screwed with my head way more than I thought it would. Structural typing was really different, I had to spend a long time rewiring my brain. But when I went back to C#, I felt like the type system was crude. I lost all the nice and easy ways of writing dynamic code and had to revert to defining surplus kludgy interfaces, delegates, etc. And in Typescript I'd finally figured out how to write null-safe code and remove almost all ugly coercions, then back in C# null references were a real possibility.