On what experience do you base that conclusion? My wife runs it, and she is satisfied with it. These tablets are fine for simple daily use, browsing, emailing, txt editing and some simple games from the store. Not meant for photo/video editing etcetc... But this all has nothing to do with the x86 UEFI running capabilities.
I can say there is no improvement in w10, in fact i got more headache trying to install 32b on a 64b system. Asus notebooks with celeron CPU. Better to just upgrade the ram or leave with it. Back in w7 days, installing 32b does doing some improvement in ram usage.
With win 8/10 you can at least install 32bit in UEFI/GPT (if the system supports it), with win 7 32bit a no go on any UEFI scenario.
You cannot run x86 uefi on a x64 cpu device. not possible as this is a limitation in the windows uefi bootloader. this has been discussed ad nauseam so many places. if you want windows you will have to use the arch for your cpu, and there is no work around using grub that i'm aware of.