Ok, I see what the trouble is, at least some of what you've identified. I'll list the issues:
1. Your genre values are using comma as a separator, and not a semicolon. MC uses a semicolon for list items. You probably used a comma long ago, because it allows Explorer to see the multiple values as a single string. When you use semicolon, Windows Explorder only shows your the first item in the file's Properties or an Explorer column. This is a deficiency in Explorer. Other file managers, such as Directory Opus, does the right thing. I would suggest that you ignore Explorer's poor presentation, and instead correct the tags as per-standard.
You'll want to replace all , characters with ; characters in Genre. You can select the files, and do this in Library Tools > Find & Replace, selecting the Genre field. You can make a Library Backup; in case something goes wrong, you can Restore from Backup. And Undo works.
2. Some of your genre's are either not self-consistent, or have extraneous commas, or are missing commas (after step 1 above, you'd want semicolons, not commas). Example:
Barbershop Quartet
barbershop, quartet
barbershop, barbershop chorus
barbershop quartet religious
...
There are also case differences, and other minor differences.
I'll suggest to you that cleaning these up is not very difficult, since you can sort on Genre either in the File List or in a Genre pane. You can directly fix the tags for the selected files directly in the File List, or by just editing the value in the Genre pane.
I would perform (1) first, and then Refresh with F5, and this will show you most of your genre's in a list. For those genres that are missing a semicolon (was comma), you'll have to edit the genre for these files and replace the space-separator with a semicolon.
I listed your genres into a file. Here are your current line counts before and after I replaced , with ;, and sorted removing duplicates, ignoring case differences:
1019 tlcmd_genres.txt
373 tlcmd_genres_semicolon_sorted_unique.txt
These are the only operations I performed on my text file, because this will be the results after you do Step 1 above, essentially. The files are attached below (zipped).
I have a tool that can help you fix the remainders (or all of them, for that matter, allowing you to omit Step 1 above), but it will require you to provide a list of all the valid genres that you really want. You can examine the tlcmd_genres_semicolon_sorted_unique.txt file and take lines such as:
Big Band easy listening mood romantic
and break it apart into the meaningful components:
Big Band
easy listening
mood
romantic
I'd be looking for the list of each unique genre, and from that entire list, I can automate fixing (pretty much) all of them, including correcting case, etc. Most of them I can figure out and are obvious, but some are not, and I wouldn't want to botch your genre data.