When the same product has a different name in every document, the reader starts counting again.
The same component is called three different things across your brochure, your website and your quotation. To you they are obviously the same. To a reader meeting the product for the first time, they are three things to work out — and the third one costs their attention.
The cost of drift
Inconsistent names do not just read badly. They make a reader re-learn your product on every page, and they make a careful buyer wonder which document is current.
How to build one
List the terms that matter — product names, components, units, process words — and agree one spelling and one translation for each, in each language. Add the ones you argue about; those are the ones that drift.
Who owns it
Someone has to. A glossary that nobody maintains becomes a fourth version. Put it where the people writing the pages can see it, and treat it as part of the product, not as an appendix.
Agreeing the terms is part of the work. See English-speaking audiences.