Delete non number containing braces from string

A string may contain non-number in braces which needs to be deleted. Input can be multiline too, for example :
input:

# (1437)  
# {19} (917) (1437)  
# {19} (1437) [1449] [2474] [2098] [1351] [508]   [969]( MONDAY) [sunday]

desired output:

# (1437)  
# {19} (917) (1437)  
# {19} (1437) [1449] [2474] [2098] [1351] [508] [969]

However the below regex instead of removing just ( MONDAY) [sunday] removes the last line completely.

$re = '/^(#\h*)((\[\d+]|\{\d+}|\(\d+\))(?:\h+(?3))*)$/m';
preg_match_all($re, $str, $matches, PREG_SET_ORDER, 0);
echo implode("\n", array_map(fn($x) => $x[1] . implode(' ', array_unique(explode(' ', $x[2]))), $matches));

In php (PCRE) flavor you may use this regex with conditional construct:

(?:(\()|({)|\[)\D*(?(1)\)|(?(2)}|]))\s*

RegEx Demo

RegEx Details:

• (?:: Start non-capture group
  • (\(): Match ( and capture in group #1
  • |: OR
  • ({): Match { and capture in group #2
  • |: OR
  • \[: Match a [
• ): non-capture group
• \D*: Match 0 or more non-digits
• (?(1)\): If group #1 is present then match )
  • |: OR
  • (?(2)}|]): If group #2 is present then match } else match ]
• ): End of conditional construct
• \s*: Match 0 or more whitespaces

Code:

$r = preg_replace('/(?:(\()|({)|\[)\D*(?(1)\)|(?(2)}|]))\s*/', '', $s);

A bit more efficient version of above regex (avoids backtracking):

(?:(\()|({)|\[)(?(1)[^)\d]*\)|(?(2)[^}\d]*}|[^]\d]*]))\s*

RegEx Demo 2