everything started with me replacing the 4x2Tb drives in my ReadyNAS Ultra 4 with 4x4Tb. First I replaced two, and all went well and size was increased. Then I bought another two disks and added those - here something went wrong; during syncing of one of the disks, we had a power loss. The sync process restarted once powered back up and all seemed well, but I actually didn't notice until some days after that the total volume size hadn't expanded and was still showing ~7.5Tb only.
I figured I'd try pulling one of the disks and inserting again, see if that would trigger a size expansion (by the way, I did reboot several times). No luck. Realized that the disk I pulled wasn't one of the two that I added last, so pulled one of those and while it was syncing I saw that it said in Raidar that it mentioned "Recovery"... ok, so I figured let's make recovery impossible and format the disk first, before reinserting.
Now here is where I messed up - was a bit in a hurry so instead of pulling out disk 3, the one that was currently syncing, I pulled out disk 1 - the other disk of the two that were added last. Didn't realize my mistake until after deleting the partitions using external USB dock on my laptop

So I removed all four partitions that were on this disk (for some reason it had 2 partitions of around 2Tb - I guess related to why the system hadn't expanded?). Following this I slotted it back into the Ultra, which tested the disk but then nothing more happened.
So basically disk 3 was syncing at around 20% at which time I pulled out disk 1. The total size of the entire system prior to all of this was ~7.5Tb, whereas this should've been around 11.5Tb according to the calculator site I found.
Am I correct in assuming that I've messed up badly and all data is lost?
I just want to be sure before I make a next move and build a new volume on the 4x4Tb disks.
Currently Frontview says there is no volume

Any help appreciated! There was quite a lot of stuff on there which is a pity, but not a big deal if it's lost. There were also a lot of pictures and movies of our little kids there - hopefully we have portions of it saved elsewhere, but definitely not all of it. Would be frustrating to say the least if such a "simple" mistake means that all is gone - would be a lesson learned though.
I'd appreciate any input in the matter, is there anything that can be done to salvage the situation?