"Update successed" - there is no such word. "Success" is not a verb. Change it to simply "Success" or "Update successful". I know - most people just smile or laugh and ignore it but Nextion is a world-wide popular product now so it should not be funny to read and the company deserves to raise to the international standards.
I'd recommend you to create a category where people will contribute to the improving the language in your product (much to be desired). Don't shy - most people here are not native English speakers either...
With best wishes,