Syncing two iMacs, iPad, iPhone with iCloud

On Syncing .......

I work in two offices were I have an iMac - 27 inch.

(one from 2015 and one from 2019).

I need / like big screen so that's is why I am not using a laptop.

Using iCloud, iPad and an iPhone I noticed problems in syncing contacts and photos.

Having solved that with an Apple support employee on iMac A I am now wondering what happens next when I start using iMac B (were i had similar issues)...

With the Apple employee I changed stuff on the iMac A.

iCloud, iPad and iPhone were, and are in Sync.

In a few weeks I will be working at the other location on iMac B, so I expect problems there again and I am not sure if I remember all details from the session with Apple support employee.

Should I take my G-drive with time machine from iMac A and just use that backup to start again on the other one (setting backup from iMac A onto iMac B) ?

(I know the other answer: buy a laptop and two screens, maybe that is the easiest way out and I will be up to date given the 2015 and 2019 iMacs are getting older ......)