Hey, i don’t know if somebody answer you.
But here is.
After you have you XML 4 in FCP, use “Title Exchange pro”, has a demo versión that you can use for only 50 subtitles.
First select in preference/convertion FCP xml to STL text
after that
preference/convertion STL Text to DCP Digital Cinema XML
You need to convert first to STL text, if you want convert directly FCP xml to DCP Cinema XML the software mark error.
You need to check the options in the convertions. Any questions, if i can i answer you.