Searching on brackets does not work in calculated field in ARCS TM

Summary:

Im getting parser issues in the TM calculated field when I would like to search a string for brackets and get the text in between the brackets.

Content (please ensure you mask any confidential information):

Example.

String: "test test test (12345)"

Calc field should return: 12345

The below formula I use should do the trick. However, the parser stumbles on the '(' and ')' as search terms.

SUBSTRING(
{JOURNALLINE_DESCRIPTION},
INSTRING({JOURNALLINE_DESCRIPTION}, '(') + 1,
INSTRING({JOURNALLINE_DESCRIPTION}, ')') - INSTRING({JOURNALLINE_DESCRIPTION}, '(') - 1
)

I get the following error when I use this formula: "Unmatched parenthesis at character 122."