Great Question, its in our FAQ on this page https://bertha.ai/yoast/ but, rightly so, we will add that answer to the https://www.ads-software.com/plugins/bertha-ai-free/ FAQ as well.
Bertha supports more than 20 languages and many more dialects. Including German (and other Latin-based langs), Russian and Japanese.
You can play around with languages by adding the input data in your own language and in your own words.
For example, Australian English is a bit different to American English, so if you add the information with the vibe and feel of the dialect, Bertha should pick up on that and provide you with results that are influenced by it.
I hope this helps and let me know if you have any other questions!
