I think the extra CHL spot opened up via the continental cup. A team Kazakhstan team won in 2018-19 but they couldn't take up the CHL spot so that went to second place Belfast. That in turn meant the EIHL place went to runner up Cardiff.
The further knock on effect meant Cardiff didn't take up their Continental Cup spot from the Play-offs. The next in line for Continental Cup would have been the Challenge Cup winner, but they'd already qualified for CHL. Next in line was league runner up, but they'd already qualified for CHL so it fell to league 3rd place. It was a tangled web.
https://www.eliteleague.co.uk/european-qualification
The further knock on effect meant Cardiff didn't take up their Continental Cup spot from the Play-offs. The next in line for Continental Cup would have been the Challenge Cup winner, but they'd already qualified for CHL. Next in line was league runner up, but they'd already qualified for CHL so it fell to league 3rd place. It was a tangled web.
https://www.eliteleague.co.uk/european-qualification
Glad I'm not required to make sense, or plan, for this!