Hi Stefano,
We were able to reproduce the reported issue and we considered this requirement “Throws error while using localization to filter menu” as bug, also have logged a report regarding this. A support incident has been create under your account to track the status of this requirement. Please log on to our support website to check for further updates.
https://www.syncfusion.com/support/directtrac/incidents/135899
Please let me know if you have any questions.
Regards,
Sellappandi R