[Bashev]

Problem

When the target store view uses a non-Latin script (Greek, Cyrillic, …), translating a category or product fails on save with:

Invalid URL key. The "-" URL key can not be used to generate Latin URL key.
Please use Latin letters and numbers to avoid generating URL key issues.

AdminhtmlCategoryBeforeSavePlugin (and AdminhtmlProductBeforeSavePlugin) translate the url_key value and then sanitise it with:

strtolower((string)preg_replace('#[^0-9a-z]+#i', '-', $value))

That regex simply strips every character that is not a-z0-9. For a Latin-script target (de/fr/it) this is fine, but for Greek/Cyrillic/etc. every letter is removed and the key collapses to a single -, which Magento then rejects — the whole save blows up.

Fix

Use the same transliteration Magento core uses to build url keys (Magento\Catalog\Model\Category::formatUrlKey → FilterManager::translitUrl).
translitUrl transliterates via Magento\Framework\Filter\Translit (which already covers Greek and other scripts), lowercases, and normalises separators.

$requestPostValue[$attributeCode] = $this->filterManager->translitUrl((string)$value);

FilterManager is injected through the constructor of both plugins.

Result

Greek input now produces a proper Latin slug instead of an invalid key:

input	before	after
Βιολογικά βότανα και τσάι	- (save error)	biologika-botana-kai-tsai
Καλλυντικά προϊόντα	- (save error)	kalluntika-proionta

For a value that transliterates to nothing, translitUrl returns an empty string, so Magento auto-generates the key from the (translated) name — no more hard error.

Notes

• Same bug and same fix in both the category and product save plugins.
• No behaviour change for Latin-script target languages.

[rhoerr]

Good to me in concept, thank you @Bashev

[SamueleMartini]

Hi @Bashev, Thank you so much for your contribution! Could you also update the changelog file?
I think the correct version number cloud be 2.3.0 if we want to view the change as the addition of support for non-Latin alphabets, or 2.2.2 if we want to consider the change as a fix.
Once the changelog is updated, I'll approve the pull request. Thank you so much!