I resolved the issue with support for screens of different densities. In this matter, I did not rely on the mechanism of Godot HIDPI. I have a global script which switches the resolution viewport, there it is possible to obtain data on the current screen resolution.
Next, I drew in SVG format elements of a theme and exported it to a raster for three different size theme: "low density", "medium density" and "high density".
Next, I added in script the variable, in which the loaded theme as a resource. I update this variable automatically when you switch screen resolutions.
And last... in:
all scenes interface I prescribed the application of themes from the variable global script.
This enough ;-)