... Uhm, when you say the SE "recognizes" the Unidisk 5.25 (connected to the normal SWIM port?) what do you mean by that? All the documentation I've seen says "Thou Shall Not Connect-eth a 5.25" Apple II Floppy Drive to a Mac", with the one exception being you can use one on an LC equipped with the Apple II card (But even in that case you have to connect it to the dongle cable on the card, not to a motherboard floppy port), and even says you risk damaging the disk controller. Can you actually format a disk in the drive and the resulting disk works? (And as what, a 140k HFS filesystem?)
As to transferring data to and from TRS-80 or Kaypro disks, there are oodles of (well, a number of) choices for doing so under MS-DOS or Linux, you'd really save yourself a lot of hassle if you could scrape up an older PC that has support for driving a 5 1/4" floppy drive. (BIOS support for these sizes evaporated in the early 'augts, I *think* there may be workarounds for forcing a BIOS type override on newer machines that still have floppy controllers but the BIOS only does 3.5" HD but Googling that is sort of a nightmare.) The TRS-80 and Kaypro both used standard Western Digital FM/MFM controllers and therefore use formats fundamentally incompatible with the GCR format used by the Apple II, and in fact the Disk II-related drives are missing some pieces that are present in drives using standard soft-sector formats. (Biggest one being the "track start" sensor.)
The one thing a PC's disk controller will (often) have trouble with is single-density formats; most (but not all) controllers are missing some bits that allow those to work properly. I *think* Kaypros are all double-density, however, and the only single-density TRS-80 is the Model I.
The people here are really good at this sort of question, BTW. I do think the short answer is that the Mac SE is the wrong pony for this job, however.
As to transferring data to and from TRS-80 or Kaypro disks, there are oodles of (well, a number of) choices for doing so under MS-DOS or Linux, you'd really save yourself a lot of hassle if you could scrape up an older PC that has support for driving a 5 1/4" floppy drive. (BIOS support for these sizes evaporated in the early 'augts, I *think* there may be workarounds for forcing a BIOS type override on newer machines that still have floppy controllers but the BIOS only does 3.5" HD but Googling that is sort of a nightmare.) The TRS-80 and Kaypro both used standard Western Digital FM/MFM controllers and therefore use formats fundamentally incompatible with the GCR format used by the Apple II, and in fact the Disk II-related drives are missing some pieces that are present in drives using standard soft-sector formats. (Biggest one being the "track start" sensor.)
The one thing a PC's disk controller will (often) have trouble with is single-density formats; most (but not all) controllers are missing some bits that allow those to work properly. I *think* Kaypros are all double-density, however, and the only single-density TRS-80 is the Model I.
The people here are really good at this sort of question, BTW. I do think the short answer is that the Mac SE is the wrong pony for this job, however.