I've just gotten into making cc wallpapers, and I know in Homecrafter plus the template is 256x512, but this is just not the actual dimensions the wallpaper will be displayed as in game, as it's taller than 512 pixels.
I screenshotted one of my wallpapers in the homecrafter display and by my measurements, if I adjust the ratio of the pixels where the width of one panel is 256 pixels, the height would have to be ~757 pixels (give or take a few).

I know when I import my texture into photoshop to overwrite the working file, and then export at 256x512, it VERY obviously stretches the image to be taller, and it does so in game as well, so why is the template/working dimensions 256x512? Will it work fine if I just adjust the working image size to match my measurements (757 ish x 512)? or will that make it freak out in some way? Or is there a better, easier way around this that I'm not aware of? Because when making my textures I have to be aware that it will stretch vertically, which makes making precise adjustments very annoying and tedious.

I believe the trick is to make them 256x768 in your photo editor. Then resize to 256x512 and do not constrain proportions. They do look squished. The images will import via SimPE at 256x768 and show up proper in game, however, those are unusable for Mac players. They must be resized down else they show solid grey.

Ahh that makes sense, thank you! It’s a shame for me because I’m using substance designer which is locked to multiples of 124 for resolution so I’ll have to see if there’s a way to work with the taller resolution.

124? Where do they even get that value. You sure it's not 128? Because 768 is multiples of 128. You could always use either Paint.net or Gimp to manipulate the images.

Oh haha oops, yeah I meant 128, too many numbers to remember . I've been using photoshop to try and adjust what I make in substance designer, but I think I'm going to try making textures in 256x256 so I can stack them up however many times on top of each other in photoshop, and adjust from there so that I don't have to worry about image stretching/distortion. Hopefully it will work well enough that I can keep using substance designer for this!

And these textures are then saved as .PNG files, before importing into SimPE (or sending them to someone who can )?

768 is halfway between 512 and 1024 (6 x 128 or 3 x 256), so it shouldn't be too difficult to make the patterns work.

There's also a small line at the top where some of the wall will be hidden by the ceiling (if you turn it on ingame), so make sure you keep that in mind if you use any decoration at the top.
(I haven't taken much notice of how much of the wall disappears, but there's probably someone who knows).