"sk178165 is listed first under Known Limitations of sk126613" <-- This should be included within the steps, not added as an afterthought at the end of the SK.
"R81.20 includes a fix" <--Customer is not on R81.20, so this doesn't apply.
"there is a workaround for R80.40 -> R81.10" <-- That's not a "workaround" that is a missing step in the documentation.
"As disabling ciphers for MultiPortal is no activity repeated every other day it is not so hard to live with it" <-- Maybe for you, but I have a customer with an outage because of this SK. This SK article has not been updated after 16 months and multiple reports of problems, sk178165 and sk126613 have not been combined, this not to have been addressed in a hotfix, and the multiportal still has these ciphers enabled by default.
If gateways are going to continue to be shipped this way, then the documentation should be spot on so that they can be quickly corrected and run as actual security devices.
Otherwise this cipher issue is going to be highlighted on any kind of vulnerability scan or pen test, and make it quite a challenge to demonstrate compliance to any reputable standard.