I wouldn't think it'd be that hard to create a Tamago faceplate if you had the correct measurements. Binary posted in his Tamago topic a scan of the Tamago faceplate with a ruler as an example for people who want to make their own.
And it especially shouldn't be very hard if you already have the faceplate that came with it, as you already have an example of how big to make it, and what will fit and what will not.
Good luck in making one. If you don't get it right the first time, keep trying.
Actually, your faceplate might work if you shaped the screeen's hole like a square instead of a rectangle.Then you put Kuchipatchi's upper lip just on top of the square's line.You change some more small details and it would work.
That's a great idea to custom make a faceplate for the Tamago! I have some glow-in-the-dark sticker material, and when I get my Tamago, I think I'll make one. The possibilities are endless. Use the faceplate it comes with as a template, and just trace it.