Hey, another 1-2-3 nerd :)
I don't have any nostalgia it, I just appreciate how thoughtfully it was designed for data-input efficiency. I actually ported the official UNIX version of 1-2-3 to Linux a few years ago, I still use it regularly. It uses some tricks to get the original UNIX binaries working on Linux: https://github.com/taviso/123elf
I had been thinking about how to add UTF-8 support, it only supports LMBCS (Lotus Multi-Byte Character Set) by default. It's actually worse than that, it stores everything internally as LMBCS but in a lot of cases can only display ASCII, so it transliterates a lot of characters (e.g. é -> e).
It's also possible to run the real DOS version in dosemu - in terminal mode it's basically indistinguishable from an ncurses application, although dosemu is just cleverly sampling the framebuffer and translating it on-the-fly.
I wrote a display driver to make that work a little better: https://github.com/taviso/lotusdrv