We have seen cases where users of H5P who have had versions prior to 1.20, language strings were camelCase, whereas in 1.20.0 (H5P) this was moved to amos compatible lower-case only language strings.

The impact to this, breaks language packs as the LMS is expecting exact matches

This was found in the language pack file: h5p.php 

https://github.com/h5p/h5p-moodle-plugin/commit/e3e340043acbbda0521718738c9b04e35a3ead8a

The fix, to not only handle the case change, We found that here:

admin\tool\customlang\locallib.php

On lines 144 we add:

$lcurrent = array_change_key_case($current, CASE_LOWER);

if (isset($current[$stringid]) || isset($lcurrent[$stringid])) {

     $current[$stringid] = !isset($current[$stringid]) ? $lcurrent[$stringid] :    $current[$stringid];

Where now, the checks is against mixed case language strings, and then returns the mixed case string (and updates the existing string with the new name). 

As per:

https://github.com/dustinbrisebois/moodle/commit/57a523c459638375b75c67fe7ca62e8de974a7ba

Adding:

on line 171 where:

if (is_null($current[$stringid]->local) && $stringmaster !== $stringlocal) {

Adds and additional check against unnecessary DB updates – if the local is empty don't run the update.