I've got a recovery disk from the 445CDT which has the same TOSCDROM.SYS as the 10x version - Toshiba CD-ROM Device Driver (ATAPI) Version 3.03
Checking the 10x file from the toscdrom package it has the same CRC / SHA checksums so it's the same and the file in the toscdrom.exe is not corrupted.
The recovery disk is attached for reference though I understand you can't use the floppy right now 😒
Just pulled out a 460CDT with the same CD-ROM drive as yours (XM-1502B N) with Windows 98 SE installed. Tested with this TOSCDROM.SYS and these settings:
Config.sys: DEVICE=C:\TOSCDROM.SYS /D:TOSCD001
Autoexec.bat: MSCDEX /D:TOSCD001
Note that there's no path specified so it should be using MSCDEX in the Windows directory, under "command" I think.
Booted up to command prompt only and the CD driver works fine and could read my Windows 98 test CD from DOS.
I wonder if the MSCDEX file you're loading from the DOS directory isn't working with the DOS version you're booting into?
Or perhaps an inclusion / setting in EMM386 is using some memory space needed for the CD-ROM drive, a longshot but it's something I faced getting PCMCIA working in DOS. Could try temporarily removing some of the EMM386 options.
Here's the Toshiba 460CDT document that shows the memory map.
The attachment sat_pro_460_tech-e.pdf is no longer available
BTW, regarding the floppy drive if it's the wide / slim type that fits into the SelectBay on your laptop and it's got the light grey facia plastic. That's the Citizen W1D in there usually and the belts have failed on just about 100% of the drives now, you need to fit a new belt to use that drive. Or you can look around for a dark-grey type Toshiba floppy drive that fits the SelectBay like from a Tecra 8000 / 8100 / 8200 - some are still W1D belt-driven floppy drives (same bezel as yours but dark grey) but the later ones switched to a direct-drive floppy which doesn't have a belt to go bad and works much better.