We've made changes in the language import tools with v17. We've created a step by step tutorial in this v17 language import support wiki page

We provide many different translations on our site but many of those translations were created for previous default designs. Within our software some text is hardcoded directly into the templates of the design. Other text is within the system text. When you visit any dynamic page in the software the "body of the page" is created on the fly by the system. The system stores the text used in the "main body" within the system. Having explained that you may not want to use the designs associated with the translations provide but you can still use the system text translations within them. Since they were created for previous versions you would most likely need to do some translation of any text added since that translation was added. What that means is that if a translation was created for v5.1.0 and you are currently at v7.3.3 you can import the system text from that v5.1.0 but you would then need to translate any of the text added between v5.1.0 and v7.3.3. All the translations we provide will be found here on our site:

https://geodesicsolutions.com/client-area/task,downloads/category_id,7/

Here are the steps to get one of those into your site:

1. If you are not using the template set from the language you downloaded you will need to create that language template set for you to translate by following these create language template set for translation support wiki article. That will create the language you can import this translation to and the template set attached to it that will require your translation.
2. Get the translation first from our site at the link above. Click on the translation you want.
3. You will download a zip file. Open that file on your local computer somewhere.
4. You'll see a directory that contains all other files and represents the translation contained. For example if you downloaded the Simplified Chinese translation for v5.1 the name of the "containing directory" would be like "my_templates_chinese_simplified_5.1". Go into that directory.
5. You'll see a text.csv file within that directory. That is the only file you'll need to import the system text translation.
6. Upload that text.csv file to the /admin directory of your Geo software. You can use your local ftp software or the file manager found in your site control panel.
7. Now log into your Geo admin tool and go to the following LANGUAGES > LANGUAGES HOME admin tool. If you haven't added the language you want to import that text to create it now.
8. Once you have the language you want to import that translation into and the text.csv file uploaded to the /admin directory click the "import" button next to that language in the LANGUAGES > LANGUAGES HOME admin tool. You now have imported the system text for that language.
9. If your translation was for v5.1 and you are currently at v7.3.3 you will need to translate any text added since v5.1. To do that you will now click the export button next to the language you just imported. That then overwrites the /admin/text.csv file with the complete system text for that language.
10. Download that text.csv file to your local computer using your local ftp software or the file manager in your site host control panel. You can translate that file in a text editor but it should open in software like Microsoft Excel or OpenOffice Calc.
11. Make your translation changes.
12. Upload it back to the /admin directory of your Geo software and click the "import" button next to the language to import those changes into within the LANGUAGES > LANGUAGES HOME admin tool.