Welcome to the darkside, squirt.
Well done, I used to use a similar 2 vessel system when I lived in the UK and owned a Bru-heat electric boiler. Now, a possible helpful hint. You have a good old 40L urn, as I do - actually I have two so I can do double side by side batches in the available time.
So first, let's recap - you have mashed in the esky using hot liquor from the urn, removed the wort from the grain, then put the wort back in the urn to boil, then into the cube. Good system but as a possible help, see if this idea floats your boat.
Instead of removing the wort from the grain, why not simply remove the grain from the wort by mashing in a purpose made swiss-voile bag in the urn, Using the full volume of liquor (i.e. no sparge) then raising the bag to drain as you bring the wort to the boil. Dispose of the grain easily afterwards.
That way the wort just stays in situ, no need for the esky or other vessels and no need to raise and lower full vessels. Of course you are doing this in the kitchen so would need to find somewhere to hang the bag to drain. I've got a skyhook hanging off a beam laid across the inside of the hatch-into-the-roof.
Hint, I've done this around 150 times now and can assure you this system (BIAB) makes perfectly good and often award winning beers with less faffing around.
The other advantage is that you only have one vessel to clean up. Not knocking your, or anyone elses' systems if they enjoy what they are doing and producing great beer as well