Hi
I tested both issues with the defualt theme and only required plugins.

1. HTML block issue is caused by Polylang plugin. The same issue happens when I choose “text” option rather than HTML block. The weird issue is that the theme works really great with Polylang, I can translate the tab title using the Polylang translation section and it works really great. The text section also works great and the translation works. The problem is with the content of the tab (text not HTML block) when Polyland is enabled and I use more than 1 tab.

The weirdest thing is that now I enabled the child theme and Polylang plugin, and istead of using tab 1 and tab 2 I now uas tab 1 and tab 3 and everything is working as expected in both languages.
How can you explain this?

2. The reason the header menu issue is not solved is becuase I have no translation for the mobile menu tabs in Polylang, unlike the custom tabs, so it can never be translation.
There is also nothing where I can choose another menu for the other language.
It works for the defualt menu or mobile menu becuase we set it in the menus section, but in the header settings where we choose a menu, we can only choose one, so I can choose for the other language?

You can be sure your theme runs really smoothly with Polylang.
The 2 issues mentioned above are related to the theme settings and header settings, which can’ t be translated.
If you find a way to fix it, you can also make sure the theme runs really well with Ploylang.

It’s impossible for me at this stage (the site is about to go live really soon) to change the language plugi to WPML so I must find a way to fix the 2nd issue as soon as possible (as the 1st issue , in a bizare way, was solved) .

Thank you