A single character class isn't going to help you here, as that will simply match anything, and you specified "*", meaning zero or more, so it'll even match an empty string!
You need the specific pattern to match, so:
String regex = '[a-zA-Z]+ - [a-zA-Z][0-9]';
Which covers all of your examples. The spaces and hyphen can be written normally, the first part ...
You have tried to make the regex using a character class, but that's simply incorrect.
You should find something like the following is more appropriate:
^.+ - L[0-9]$
Matching the whole value (start at the beginning with "^" and end at the end with "$")
Allowing any sequence of at least one character with ".+"
explicitly matching space, hyphen, ...
The regex function only tells you if a regex pattern was found in the supplied string. It won't count the number of occurrences, and it won't work on a collection variable.
You could use a loop on the collection variable to check each variable individually. You can then use a decision element to check if the individual variable contains the .com. This ...