<?php
$source = '<0><1><2><3><4><5><6><7><8><9><10><11><12><13><14><15><16><17><18>The next 11 keys can change the SWING from OFF (50%) to <19><20><21><22><23><24><25>80<26><27><28><29><30><31><32>% during arpeggiator or sequencer operation.<33><34>';
$cnt = 0;
echo preg_replace_callback('~(?:<(?:{\d+}|【\d+】|〖\d+〗|\d+)>)+~u', function($m) use (&$cnt) {
return '['. ++$cnt .']';
}, $source);
[1]The next 11 keys can change the SWING from OFF (50%) to [2]80[3]% during arpeggiator or sequencer operation.[4]
Output for 8.3.5
Warning: PHP Startup: Unable to load dynamic library 'sodium.so' (tried: /usr/lib/php/8.3.5/modules/sodium.so (libsodium.so.23: cannot open shared object file: No such file or directory), /usr/lib/php/8.3.5/modules/sodium.so.so (/usr/lib/php/8.3.5/modules/sodium.so.so: cannot open shared object file: No such file or directory)) in Unknown on line 0
[1]The next 11 keys can change the SWING from OFF (50%) to [2]80[3]% during arpeggiator or sequencer operation.[4]