I already implemented a method which takes the name of the needed layout, iterates through all the custom layouts and gives the layout back as soon as the name is found.
Unfortunately the name changes when the user uses Office in a different language.
The question is what translates the custom layout names and how can I use the same translation within my VBA code?
Any ideas?
The standard layouts in a new blank presentation have different names in different languages, but you don't need to identify them by name. Each standard layout can be identified with SlideLayout.Type. Here's is Microsoft's enumeration of these: PpSlideLayout enumeration (PowerPoint). These are language independent.
Custom Layouts that you create will all have the Custom layout type. But their names won't change, so you won't have an issue with them.