There's no reason why implementing a language in itself would be special, it's not dealing with fringe situations in any sense of the word. It is traditional to write compilers in the very language they compile, except for slow interpreted languages, and a compiler is a very well-studied type of program that includes a variety of different types of code such as straight text processing, error reporting, and recursive data structures. Compilers are often used as test beds for new language features, famously, Niklaus Wirth would measure language improvements based on how much they would improve the language's compiler.

Think about it this way: a TypeScript compiler takes a bunch of text as input, and produces a bunch of text as output. That's not really special or weird, is it?

(The only hard part is the “bootstrapping problem” which is what happens when you want to write a compiler for language X using language X, but you can’t compile it because you don’t have a compiler yet.)