Change #1186121 had a related patch set uploaded (by MusikAnimal; author: MusikAnimal):

[mediawiki/extensions/CodeMirror@master] CodeMirrorWikiEditor: query for search btn within current WE context

https://gerrit.wikimedia.org/r/1186121

Change #1186121 merged by jenkins-bot:

[mediawiki/extensions/CodeMirror@master] CodeMirrorWikiEditor: query for search btn within current WE context

https://gerrit.wikimedia.org/r/1186121

In T403995#11160888, @MusikAnimal wrote:

I'll note that for what you're trying to do, you may (or may not) want to use CodeMirrorChild instances.

Thanks for the guidance. But I think my users should be able to toggle CodeMirror in different editors independently (e.g. one comment has complex syntax while another hasn't).

(But I've already stumbled upon other issues with multiple CodeMirror instances: clicking <label> of preference checkboxes in the second editor checks the checkbox in the first editor since they have the same input IDs assigned in codemirror.codex.js#L121. But it also indirectly checks the checkbox in the second editor thanks to the hook in codemirror.preferences.js#L614

		// Update the checked state when the preference is changed.
		mw.hook( 'ext.CodeMirror.preferences.apply' ).add( ( pref, enabled ) => {
			if ( pref === name ) {
				input.checked = enabled;
			}
		} );

(but doesn't change the appearance of the editor!). Don't have time to create a task yet...)