I have spent 2 days fighting with Calamares but didn’t get anywhere… I don’t think the install with unencrypted /boot is supported though - I have seen few requests thrown at the Calamares dev team, but no mention of this being implemented. On the contrary, explicit comments that it makes no sense to implement it as it is not common scenario 
I read through your post re manjaro-architect package Maintainer(s) wanted - #20 by winnie - super helpful, thanks. I tried KDE install (which is the DE I’m after) but ended up with broken system. XFCE though, although I only tried it for fun, seems to give fully working system atm - with all correct drivers set up and manjaro branding out of the box. If testers needed for KDE LUKS2 install scenarios, count me in - don’t know if I can be useful given my limited time, but I have spare Vostro at hand, happy to help.