@infograf768 I'm not a com_localise expert but I think this roughly get this component working on J4 (the ui isn't pretty but it is functional). It should also keep working fine on J3 too.
Use JLanguageHelper instead of JLanguage on 3.7 and higher
Use namespaced version of ArrayHelper (we already used it one place in the translation model)
Remove most uses of JError in J3
Stop loading mootools for core.js (I don't think we're even using it?)
Use bootstrap modal rather than legacy modal script
Use newer formvalidation script that's decoupled from mootools
Give asset table a default id of 0 (this matches the current J3 asset ID column properties in 3.9.27)
@infograf768 I'm not a com_localise expert but I think this roughly get this component working on J4 (the ui isn't pretty but it is functional). It should also keep working fine on J3 too.