you can check the progress of the TI emulations on the MESS Wiki or in more detail on www.ninerpedia.org.
If it says "No such device" it seems that either the floppy image is not in the correct device, that the image is unreadable (wrong density, but this should output another error) or that you just don't have a disk controller set active. The ".G" file is the GROM dump which is now contained in the RPK, so you don't use it anymore. So please check:
- The disk image should be put into flop1, the cartridge goes into cart1.
- The HFDC floppy controller is the preferred disk controller. When I switched from dip switches to configuration switches I dropped the defaults; I fixed that in the recent svn.
Please do not use the "bin", "C", ... dumps anymore. I think all cartridges should now be available as RPKs.
The message "One or more ROMs..." is very likely due to a missing optional ROM in your ti99_4a(e).zip and is not related to the cartridges. In particular, I added P-Code support (UCSD Pascal, 0.133). Although those ROMs which are loaded as optional are only required for the P-Code card which is only rarely used, the emulator will issue a warning that ROMs are missing. I'm already thinking about another extension mechanism; until then I can only suggest you to ignore that or get the ROMs for the P-Code card from somewhere.