There are REGEX tutorials here on MR. That is where I learned what I do.
Calibre (and Sigil) use the PCRE dialect.
There is also a link to a REGEX cheatsheet, just remember The PCRE does not support all those.
\d is a digit
.+? is a not greedy wild card for 1 or more characters
\s is any kind of space
S the wild card should stop at the first space
try escaping the dash \- and the square brackets \[ \]
[A-Z], [0-9] is a range AFAIK it should have been treated as a literal in this case