Manual translation using Poedit
Alternatively, you can translate manually with .po file, pls. follow the instructions:
1. Take file languages/thegem.pot or xx_YY.po from theme directory.
2. Open this file with Poedit software
https://poedit.net/
3. Translate necessary strings to your language.
4. In Poedit open Catalog - Settings and set Language to Translation to xx_YY.
5. Then save the file as thegem-xx_YY. (You must have two files thegem-xx_YY.po and thegem-xx_YY.mo.)
6. After that you just need to put these files to the wp-content/languages/themes/thegem-{locale}.po folder.
The same can be done with TheGem Elements plugin, just put your files to the
languages/plugins/thegem-{locale}.po folder.