Creator here.

There is a sweet spot that I've found between icon-ifying everything and keeping written instructions in. The mobile versions have a "guiding hand" that also leads through the first level of what exactly to press, but later on, levels like procedures and loops really require a written, accompanying explanation which cannot come across with pictures alone. So, you will see an image that explains the concept as well, but the two together are what works best.

A voiceover/actor would be ideal, but I have yet to search too far in that direction, and would then need those voiceovers translated to the other languages, etc etc.

Is reading without sounding anything out not expected by 5?

Essentially, you can't really force these skills on kids. These things happen on individual pace for every kid out there. Some are better at art, some are better at speech, some are better at math and some learn to read earlier than others. That's why the school starts when it starts. By that time development seems to even out across the board.

No, it is not expected. The part of brain responsible for reading can develop any time between 4 and 7 years old. Most are there by 6 and plenty of 5 years old are not there yet.

By the time they are 8, there is no difference between former early readers and other kids, so there is no reason to worry about it.