> select="substring-after(normalize-space(.),',')"/>

what you want there is

select="normalize-space(substring-after(.),',')"/>

but easiest is not to tokenize on a , (which leaves dangling white
space) but to tokenize on a comma followed by optional white space
tokenize(.,',\s*')
then the token will never start with white space as any such space will
be taken into the token separator.

David