Theme is not 100% ready for translation. Example: https://imgur.com/a/oszCWBe
These 2 fields in the metabox are not translatable, and dev has known about this for a year. You have to buy additional plugins to translate them! In the Bimber theme, even metaboxes are 100% translatable, so you can do it, but nobody here wants to! There is no frontend post editing system (as in the Bimber theme) - to edit the post (by any non admin user), you need to provide the user with the backend and add additional plugins for backend security and... it turns out that this is a problem because metaboxes are not translated! (...)
Our theme is fully translatable and we have frontend post editing system more advanced than our competitors. There is no need to purchase any plugin for fully translating theme, WPML is required for multilingual setup and not for translating theme in your language, which is same for all the themes. We're going to open open report and request appropriate ban from Envato for continues abuses and misleading comments from this account.
"Our theme is fully translatable"
Yes, but on condition that you buy an additional plugin (WPML) and use it together with Loco, which you have confirmed yourself and now you are denying it: "They should be used together".
Look at this snapshot: https://imgur.com/a/UkjdCi3
"We have frontend post editing system more advanced than our competitors"
It's not about what publishing system you have, it's about you don't have an editing system. The published post has to be edited from the backend - Bimber had the same problem, but he fixed it. There is no word in your documentation that an already published post can be edited from the frontend without access to WP-Admin.