US qwerty and Czech qwertz (or qwerty? in your case) are incredibly similar, which makes them easier to mix up. The keys that you type the most of - alphas, spaces and numbers - are positioned on the same keys, nevermind the modifier.
In Arno's Engram, only X is in the same position, and on a split keyboard, the numbers are positioned differently also in my layout.
Part of what makes splitboards appealing is that beyond the alphas, you figure out the layout that's the most optimal for you.
For instance, I have arrows on my homerow under keys that are HTSN on the alpha layer (mimicking Vim's HJKL), but others can have completely differently positioned arrow clusters.
Keep in mind, that if you don't want to keep thinking about it, you can lurk at the r/KeyboardLayouts subreddit, or just slap the appropriate version of the Miryoku layout onto whatever you have.
You can also have a ton of macros and combos and tap dance and other doodads if you feel like doing that and have a big enough MCU, which you'll probably have