A full example of your event could be handy. Depending on your full event data you can be a bit more precise with regex. You can use what ever precedes the location name and since you have parenthesis you can also use them as a boundary for your capture group
Example:
event text whatever pre location SINGAPORE (ABC) event text
event text other info pre location HO CHI MINH CITY VIETNAM (ABC) event text
Regex:
location\s+(?<location>[\w\s]+\([\w\s]+\))
Explanation:
Both names would be properly extracted since I bounded my capture group between "location" and a set of "( )" with whatever word and spaces inside. Whatever word composed by a-zA-Z0-9_ ( \w ) ou a blank character ( \s ) will be captured.
Live test here:
https://regex101.com/r/5lMFCJ/1
Hope this helps!
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