It looks like you've not configured multilingual site properly. Pls check out this documentation for more details: https://www.joomlart.com/documentation/t4-framework/multilingual-configurations
With your site, I re-created template styles for each language for you (please don't delete them)
On mobile, it's loading off-canvas
position but when I checked modules, there is not any module assigned to this position, I also created these Menu modules for you:
Again, you should create everything for each language and assign associated content for each.
I do hope this makes senses.