Can you give me tips, how I can get the blender open source code, change text field to the Russian translation and publish it as an kind of addon
Blender already comes with translations. Open Blender's preferences (Edit > Preferences) and go to the Interface tab. There you can enabled the checkbox for the Translation option and select the desired language. The Automatic option will use your OS language configuration.
You have the option to enable Tooltip to translate the tooltips that appear when you hover over UI items, Interface to translate all labels in the interface and New Data to translate data-blocks such as material and object names.