The server resource files, SPCServerResources.resx and SPCResources.Resx, are located in the Localization subfolder of the Smart Construction installation location (browse to [Drive]:\Program Files (x86)\SmartConstruction\2019\Customization\Localization).
Make copies of the original SPCServerResources.resx file and SPCResources.Resx. Save the files as backup copies in a different location than the Localization subfolder, in case you need to recover them later.