Information messages about plugin actions are corrupted for the Russian language

Issue Summary

Some plugin-related information messages (installation/enabling/etc.) shown by Univeral Plugin Manager are corrupted for Russian localization.

This is reproducible on Data Center: (yes)

Steps to Reproduce

1. Navigate to your profile settings and change the language to Russian (or set it as default on the system level).
2. Then go to Administration (⚙) > Manage Apps and try to install or enable/disable any plugin.
3. You will notice that information messages about the current activity will be corrupted (the Unicode escape sequences will be shown instead of actual Cyrillic letters)
   

Expected Results

Information messages will be shown correctly

Actual Results

The information messages about the current activity will be corrupted (the Unicode escape sequences will be shown instead of actual Cyrillic letters)

Workaround

Currently, there is no known workaround for this behaviour (except for temporarily using a different localization). A workaround will be added here when available