Hello, Perino. I will describe process step by step, it's easy, you can do it:
1. Install your language (or create new)

2. Turn on developer mode / install the "Odoo debug" extension in your browser. Be sure you turn it on. Since you turn it on, you see additional tabs in the Settings menu.

3. Go to the Settings - Translations - Export Translations

4. Choose your language, CSV format (it's the easiest way to transform it in Excel), and "Products & Pricelists" application. Then click the Export button.

5. Then extract .CSV in your Excel (Tab "Data", Get Data from txt/csv). Be sure about the encoding (in Odoo it is UTF-8 by default) and then load.

6. Find "product.template,name" in the "name" column (or any other field you want to update), and write down your names in the column "value" (you can easily match appropriate rows by "scr" column).

7. Save your translation in .CSV format.

8. Go to Settings - Translations - Import translations. 

8.1. Put the "Name" of your language in the Import pop-up "Language Name"
8.2. Put the "Locale Code" of your language in the Import pop-up "Code"
8.3. Upload your .CSV file, and click "Import".

9. Enjoy your brand new translations: