Apart from only working on one letter SQL tables, you are either omitting whitespaces before the open parentheses or, depending on the SQL and regex engine/string syntax, over-escaping your expression parentheses.
Check:
[A-Za-z]+\\s*
if it doesn't work and the plus sign is not recognized,
[A-Za-z][A-Za-z]*\\s*
and whether it's \\\\( or just \\( (it should be the latter. But better be sure).
This supports names such as Antinoo and cUsToMeRs, but not Invoices_New or Suppliers2014. You might want to add numbers and underscores to your regex. Since table names probably won't start with numbers, you'll want
[A-Z_a-z][A-Z_a-z0-9]*\\s*\\(([^;]*)\\)