JSFiddle - React, Tailwind, and code Playground

HTML

<div id="output">
</div>

CSS

#output {
    font-family: monospace;
}

JavaScript

var test_cases = [
    '(1)',
    '((1))',
    '(((1)))',
    '(1) (2)',
    '(1) ((2))',
    '((1) (2))',
    '(1)(2)',
    '(1)((2))',
    '((1)(2))',
];
    
function matchValidTags(s) {
    if( s.match(/\(\(\d+\)\)/) ) return null;
    return s.match(/\(\d+\)/);
}
    
function process(s) {
    var m = s.match( /\(+.+?\)+/g );
    $('#output').html( 
        $('#output').html() + '<br/>' + 
            m.join( ', ' ) + ' --> ' +
            m.filter(matchValidTags).join( ', ' )
    );
}
    
test_cases.forEach(process);