Do not try to parse WinSCP session log file.
Use XML logging for your purposes.
https://winscp.net/eng/docs/logging_xml

I'm attempting to output this logging data in my own tracking sheet. I need to know what each of these pieces mean in the log file. I see they're separated by a semi-colon, so I'm assuming each piece has it's own meaning and definition. I'm not seeing anywhere on the website where it states a definition of each field in the log file.

2019-05-20 10:02:32.696 SAMPLE_TEST_FILE_201905182300.txt;
-;
13028800;
2019-05-20T06:30:02.000Z;
3;
"TEST" [686];
"my_test" [5433];
rw-rw----;
0