Rommable cd filesystem could be handy, it would allow mounting cd-rom with any boot disk which has normal 2.0-3.1 c: drawer. Could be time saving and make OS installation much easier, even if boot from cdrom wouldn't be possible.
I don't see much advantage to putting the CD file system in kickstart if it is not mounted early enough to boot off of. Most modern media has room to put the CD file system on the disk. Floppies would benefit as they have limited room but who is trying to use a CD with only floppies?
An AmigaDOS script can simulate booting off CD. Let's call the script BootCD.
SetPatch quiet
failat 31
assign T: RAM:
makedir RAM:ENV
madedir ENV:SYS
echo "WB3:S" >ENV:SYS/nv_location
mount CD0:
assign SYS: CD0:
assign DEVS: SYS: DEVS
assign ENVARC: SYS:PREFS/ENV-ARCHIVE
assign FONTS: SYS:FONTS
assign KEYMAPS: SYS:DEVS/KEYMAPS
assign L: SYS:L
assign LOCALE: SYS:LOCALE
assign LIBS: SYS:LIBS
assign PRINTERS: SYS:DEVS/PRINTERS
assign S: SYS:S
assign C: SYS:C
CD SYS:
execute S:Startup-Sequence
EndCli >NIL:
Boot off your normal bootable media and execute the script. The 68060 or 68040 support code is loaded first. For CD32 compatibility, nv_location is set to the HD for saves since most Amigas have no NV memory and the CD can't be saved to (change "WB3:S" to the desired save destination). The script may need some refinement but this should work for some CDs.
About CD Filesystems :
I have tried without luck
CacheCDFC
AmiCDFS
ASIMCDFS
BabelCDFS
CD32/CDTV cd filesystems
Only one which I haven't tried is that Elbox cd filesystem.
A file system may fit in kickstart and even work sometimes when it is not ROMable. It doesn't appear you have even been that lucky.
The CD32/CDTV CD filesystems are obviously ROMable but the drives are not IDE/ATAPI. They may lack the interface to specify a different device. The CSMK3/CSPPC has a CD file system in the flash which allows booting but it is limited in what formats it supports and may also be specific to the accelerators SCSI device.
I am not the expert on ROMTags and ROMable modules. I can disassemble the modules but I don't know what to look for. There are guys who could look at the ROMTags and hunk sections and tell you in a few minutes what is ROMable and what the module will do if placed in kickstart.