I haven’t read your journal yet (will do that soon!) but it’s worth a try in a new space. Are you planning to use the pen there to complete their bond? If you find taking this step was a mistake it’s always good to go back to where it was working i.e. For you – the mudroom.
Edit to add: Ok, just read your journal. It’s going nicely. If it were me, I would actually continue a little longer in the mudroom and start to introduce things for them to do together, like eat food, share a litterbox. Then move onto the pen after they’ve spend longer time together successfully in the mud room. The pen in to room where their cages are would be more semi-neutral. You can experience some nipping and chasing when bringing into a new bonding area. Hopefully they’ll get it out their system and settle quickly. I found putting sheets around the pen helped when I used one.
As to your other question regarding their habitat – yes, I would think a thorough clean and joining of the 2 should be enough. If not, then they can go back to the pen and you may then have to a complete overhaul. Main thing is try not to rush to the next step. 