Hi,
It seems like you made the changes to the language files which were present in the local languages folder.
You needed to put the translation files into the system folder ie
wp-content/languages/plugins folder.
Please contact your webhost to provide your website's backup of before you updated the plugins.
Then from the backup put all the PO/MO files of all the plugins of the polish language into the
wp-content/languages/plugins folder.
This is the correct translation guide :
https://vibethemes.com/documentation/wplms/knowledge-base/translate-using-loco-translate-plugin/
If you follow this guide your translations will remain intact even after updating the theme and the plugin.