How about this
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
How about this
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