(Ah, fair point. The original is actually "I don't suppose you're going to tell me why
you're here, of all places?". I was rendering it down to just "I don't suppose you're going to tell me why you're here".)
The back-translation here, short as it is, is pretty spot on
. I'll adopt "sitelen toki" - written speech works, indeed.
"Many people will know about" => "He'll be famous". I don't see one can get closer.
The most tricky bit is "jan Ari li sama pi jan sewi pi sitelen musi." => "He'll be a legend". Literally, I wanted something like "he'll be like the awe-inspiring people of stories". Perhaps "suli, important" would have been better than "sewi", but I was trying to avoid "large".
Otherwise, bang on!