You should probably submit a new support ticket with this so that it is brought to the attention of the developer https://support.advancedcustomfields.com/new-ticket/. Pretty sure that if WP supports CodeMirror natively that we can expect to see an ACF field that uses it at some point.
I too would like to see this supported by ACF, I have always wanted to be able to give some admins the ability to add code to a site other than a simple textarea field. But the support for the existing code field add ons in not as good as I would like. Probably the only way I would ever trust using a field like this is if it’s built into ACF.