Hi paky50
I can login now and see that the template styles are not configured properly for multilingual site. Pls check out this guideline for more details: https://www.joomlart.com/documentation/t4-framework/multilingual-configurations#template-style_jadoc
Like menus , modules, you need to duplicate template styles for each language. The basic steps are:
1/Duplicate template style >> set a default template style for each language:

2/Duplicate default navigation and assign associated menu of each language:

3/ Assign template style to the menu items as you wish:

I updated EN for your site, you can update the same for other language.