Hi @pavol_krasnansky. You may want to consult someone at Autodesk about the best way to translate your drawing document(s) from one language to another. That is a really large and complex task to tackle by iLogic code if you are just planning on using a find & replace type strategy on all the many possible types of objects that may be present within an Inventor DrawingDocument that can contain text. There are several objects within a drawing that we still do not even access to by API or iLogic code yet.
If you want to keep trying to tackle this by code, the code will likely need to be greatly expanded due how many different types of objects it may have to process through, and will likely need a lot of potential error avoidance built into it, to keep it from erroring out part way through the task. Many types of things that can contain a TextBox, may have several different aspects to them also, such is the case with Borders, TitleBlocks, SketchedSymbols, and some others, where you may need to check within the TextBox.Text property, within the TextBox.FormattedText property, and when it represents a prompted entry, you also need to check its currently shown value with one method, then set an edited value for it using a different method. Then the FormattedText usually contains XML tags, which is another programming language, and replacing something in that may break its functionality, but may be necessary.
I attached a text file below with some code in it you can play around with. Within that I decided to split several of those larger, more complex objects out into their own separate Sub routines, in an attempt to keep the main routine's code a bit cleaner, and easier to read through, without getting overwhelmed. As you can see, I am only covering 3 possible objects, and the overall code is already pretty long. I mentioned many other possible object types you may want to look into, but do not have time to create working, error free solutions for all of them right now.
Wesley Crihfield

(Not an Autodesk Employee)