Yeah, you got it! After 30 years on the internet I should know by now whats understandable for others and what's not (I honestly just realized that English speakers don't say 'tja'), but alas.

We have a sound we usually spell “yeah”, which can also be an informal “yes” but can also server roughly the role of a “Well, “. The same spelling is sometimes employed for a cheer that might otherwise be spelled “yay” and sounds very different, though.

I can think of at least one regionalism or dialect that has something that I bet sounds similar to yours, that might even be used the same way yours is: “valley girl”.

The real tell was the spelling. We don’t usually use “T” to harden a phoneme at the start of a word—we do later, though, as in “itch”—and we don’t use “J” that way. “Ch” is probably the closest we’ve got to what you were going for with “j”. If a native English speaker were trying to reproduce the sound you’re going for in text, they’d not have spelled it that way unless trying to make it appear foreign.