I’m not sure if Calyx is the right CustomRom for you if you have a lot of customization/colors/etc. needs. ^^
I think all the custom roms have their goal/idea. Calyx is clearly described as Privacy, Security, prevent tracking, Free Software, etc. focusing
(–> About CalyxOS / CalyxOS - Wikipedia)
These goals totally fits at least to my needs (and that it works stable as the FP4 is my daily driver → I can say after some weeks using it this is the case … even CalyxOS is still not yet official)
Even though I have to admit that I also tend to bring back things working the same way as on my old phone (the FP2 same as for you afaik). 
The biggest loss for me up to now is the missing notification LED, but this is a Hardware problem and I cannot blame Calyx for that.
I also adjusted the font size as a first step as it felt to big for me (Settings → Display → Appearance → Font-Size → one level down from Default to Small). Apart from that I have chosen my preferred launcher some time ago (https://kisslauncher.com/) and I think if you have one as well it will always bring back more or less the same look and feel.
Agree!