It's impractical for all actors to be fluent in every language, and at some point it impacts their ability to be successful in different markets without dubbing. I'd much rather actors can at least speak passably in one language and have AI fix the problem than to have another voice actor overdub it which 100% makes it less authentic to the performance. (Ex. Crouching Tiger Hidden Dragon where the actors gave their best shot at once dialect but it was a cringeworthy performance to native speakers). This is no different than studio recordings for albums being super clean renditions with perfect vocals vs when a band tours and the performance being less than perfect. We all strive for perfection and once achieved, it can be hard to replicate consistently, when on a tight schedule. The same thing goes for vocal coaching, in a short period of time, you can pull off that accent perfectly a few times, but under the stress of performance, you may lapse. I'd rather the actors focus on their core performance and less on the infrequently used language skills that they likely won't use again in their next project. Timebox the effort, and when it doesn't come out polished enough, we have AI.