Thank you, that worked!
For anyone that stumbles into this, the solution to load a firmware into the EM7411 is to make sure you specify BOTH the tty and cdc devices (the -d and -p flags), AND the download mode is set to 1 (the -t 1 flag). The final command is:
fwdwl-litearm -d /dev/ttyUSB0 -p /dev/cdc-wdm0 -t 1 --modelfamily 4 --fwpath "./" --cwe SWI9X50C_01.14.03.00.cwe --nvu SWI9X50C_01.14.03.00_TMO_002.005_000.nvu