I've had those Givi topcases with a lot more than the nominal 5kg they are rated for and never had a carrier plate break on me, even when off-roading.
The Versys pic from Mexico above was on a 2 week trip, the topcase had my laptop (probably 2-2.5 kg by itself), clothes for about a week, toiletries, one pair of shoes, chain lube, etc. etc. Over 10 kg if I had to guess. No issues.