you need 4 keys for basic iso layout, iso enter and the 1u next to it, and same with lshift and the 1u next to it. the two 1u are missing in the pictures.
Placing Latin and Cyrillic legends in a single row makes it difficult to focus on the one that is relevant for the user at a particular moment.
The font used for Cyrillic is not a natural extension of that used for Latin. Letters are out of proportion, Й looks like a small letter instead of capital, С is just plain wrong shape, and stencil cuts in Б Ь Ъ would be better placed as in Ы.
JamesNguyenIt refers to allowing any lighting on the keyboard to shine through the keycap, this is common on rgb keyboards like the corsair k70 with its "Shine through" legend.