I have three little plants of red cup gum eucalyptus/Eucalyptus Erythrocorys on my windowsill. They seem to thrive. The leaves should print red but it will be a long time before they do so.
You can buy the seeds at Jungle Seeds. They sprout easily. I had them on a wet paper towel on a small plate, all covered with cling film to keep moisture in. After about three weeks some of them already had two tiny leaves. That’s when I planted them in pots.
Many thanks to Ingrid for sending the link to me.