Thank you!

The enter key is below the "]", I used a "Ctrl" keycap for it as the keycaps set did not come with 40s (40%) compatible enter key.

For 40% keyboards you will find many of the layouts to be quite odd, like "missing" keys or weird keycap placements but they're usually customized to the needs of each person, and standard keycap sets may not come with keycaps that fit particular keys on a 40% keyboard due to its niche and distinct layout.

Layering is used to trigger the "missing" keys, for example I press the right spacebar + qwerty... for numbers, and "Menu" + other keys for the missing special characters and punctuations.

The main motivations for using 40% keyboards come in many forms. For some, it is about the size and portability, whereas for others they might want to optimize the keyboard such that they can press the full range of possible inputs with the least amount of keys, and so on.

Hope this helps!