Hello Vlad,
Yes, it is possible. You will need to use the Modify User Web Interface action and a Business Rule triggering After updating a user. The action form will contain only two properties. For example, you can use Adaxes custom attributes (e.g. CustomAttributeText1). The Business Rule will trigger only after setting the two properties and will run a PowerShell script that will output the transliteration results. If you need help with the script, please, specify what exactly you need it to output. Should it only change the letters in the values entered on the action form or build a different one? Any additional details would be much appreciated.