"I am trying never to say it."
Translation:Snažím se to nikdy neříkat.
No, that order is not accepted and is not acceptable :)
To is a clitic here. Clitics are usually the second word in the sentence. As there are two clitics: se and to, se having the higher precedence, to is placed right after it. -> Snažím se to nikdy neříkat.
Disclaimer: I am learning, too!
Because "se" generally has to be in the second position of the sentence (or clause), I think you could either (1) leave out "já" or (2) move "se" in front of "snažím," if you want to keep "já" where it is.
Duo also accepted "snažím se nikdy to neříkat" when I used it. My thinking about this word order was that "to" appeared in second place in the second phrase, but perhaps Duo should have marked me incorrect?