I once tried buying this software for the company I worked for, but by that time no-one would sell it to me
I don't see why your app shouldn't also work under Warp/eComStation - I don't think you are likely to be using the multiuser/remote desktop capabilities of Citrix. Why not try it?
There is likely to be some problem with new hardware on such an old version of the OS. Can you try perhaps installing the IBM1FLPY.ADD from a Warp3/4 install onto it?
If you start to try to many drastic things, you need to have a set of boot disks on standby, or at least another way of booting it....