Hi there,
Thank you for getting in touch with us, we do appreciate your time.
I have run a few tests with Polylang and WP Go Maps and it appears that the maps load correctly and are translated correctly where applicable.
I did however notice that you cannot set specific translations in the map components, as it appears that Polylang will just translate the page content.
We have integrated with WPML to achieve being able to translate separate strings in the map components if you’d like to look into using WPML instead.
With regards to adding markers, yes you may add unlimited markers in your Map Editor (Maps -> Maps -> Edit).
I hope this answers your question?
Kindest Regards,
Matthew