Hi!
I tested this on iOS 18.4, and it seems to work. I tested with the "A" and "Return" to type into the address bar of Safari. Both seem to work.
I also tested on:
https://www.toptal.com/developers/keycode
(Note that you have to focus the textfield for this to work)
Could you let me know if there is any detail I'm missing in recreating this issue?
Note that it's a good habit to "Forget" the device if you go between different keymaps since this is cached for the Bluetooth device.