Please ensure that you are testing FFCore v22.214.171.124.
There's no specific syntax. If the name is a valid name at the DFE then it should map as expected.
FFCore queries the printer for information and uses that information to populate our printing UI (this is different vs FFProM).
FFCore also stores that information in an XML file.
Go to the <FFC install dir>/Config folder in your FFCore server. There you will see a number of .xpaf files. They are named using the printer and queue name.Can you send me the file for the relevant printer destination via private message?
If the string mentioned below (T_MOHK_100lb_18x12) is not in the file then the DFE did not report that as a stock name. Sometimes there are extra spaces in the xpaf file which also need to be in the manifest...