Here’s my take. If you want to write a text-adventure platform for an 8KB MSX machine, do it, but I think you would benefit from implementing a toy Z-machine interpreter first. Understand what it does and doesn’t do, and how you would improve upon it, and what parts of the Z-machine design you’d want to reuse.
Which is to say, I’m pretty sure you’ll find that there are parts that you’d want to reuse; quite a lot of parts, actually.
If the end result is a Z-machine transpiler that can take Z-machine games written in PunyInform and run them in 8KB environments, well, great! If the end result is a “Wys-machine” that compiles PunyInform directly into something else, that’s fine, too.
And if you want to design your own language, do it, but just be aware that recruiting authors will be extremely difficult. If you’d have fun with this even if nobody else used it, then definitely do it.
But if you won’t have fun (or feel accomplished) unless you can recruit authors, then, beware, because that is the hardest task you’ve discussed on this thread, by far, and the most likely to actually Fail to occur. As I’ve said to other would-be designers of IF languages, the path up this mountain is littered with the frozen corpses of others who have tried and failed to reach the top.