Paweł Wołącewicz 

I'll start by pointing you to this article which may be worth reading as you will need a custom XML filetype for this file since the translatable content is all in attribute vales which are non-translatable by default:

https://multifarious.filkin.com/2014/06/01/custom-xml/

Basically you need to create a rule, using XPath, to extract the translatable content from the value attributes.  Based on your shared example this would do it:

Thank You for the quick reply.

I try to create new rule based on... and only just which file type because after pressing 'New' button in 'File Type', new dialog window opens 'Select type'.
Here there are three XML-file types: XML 2, XML (Embedded Content) and XML (Legancy Embedded Content).
Which one should I choose?

Thank You for the quick reply.

I try to create new rule based on... and only just which file type because after pressing 'New' button in 'File Type', new dialog window opens 'Select type'.
Here there are three XML-file types: XML 2, XML (Embedded Content) and XML (Legancy Embedded Content).
Which one should I choose?

Choose XML 2 because XML 1 will soon be phased out.

I done so!
Now it works perfectly and read all of the strings.

Thanks a lof for help :-)