Hi,
We would like to understand better what is currently not being translated. In short, there are two different “things” that could be translated: the language definitions and the database contents.
An example of a language definition could be the strings “Book Now” or “Rooms”, while we call a “content” created through Vik Booking something like the name or the description of your rooms i.e “Double Room Superior”.
You can translate anything into your preferred language(s), but depending on what you are translating, the system “responsible” of such translations will be different. In fact, all the language definitions are contained inside the .PO and .MO files of Vik Booking, which are loaded directly by WordPress depending on what’s the currently active language on your website, either front-end or back-end.
Instead, contents like the names or the descriptions of your rooms will be translated by Vik Booking and its internal functions, but Vik Booking will “ask” the WordPress framework what’s the currently active language in this case.
Shortcodes and their language attribute will not help you in this case, the language filter of the Shortcodes in Vik Booking is only needed to have a different URL for the same page, but for other languages.
That said, any third party language plugin could obviously influence these behaviours, as they can dynamically change the currently active language. What we can tell you is that the plugin you mentioned is pretty common among our clients, just like 2 more popular language plugins. Honestly, we do not know how such plugins were set up, but as soon as they set the proper language in your site (front-end and/or back-end), Vik Booking will read it by using the WordPress native functions to load additional language files (.PO + .MO) as well as to apply the translations on the contents provided.
Just for your information, on our website everyone can contribute on the translation files for our plugins for then downloading the .PO and .MO compressed files.
I hope this helps. We invite you to reach out to our technical support team by using our website should you have any deeper questions. Thank you.