When you start alphabet ,1 you don't learn the actual alphabet first. You just learn random letters. I have a suggestion to learn the alphabet, one by one. It would be easier for some. :D Just a suggestion!
I find the sequence as it is now very good: We are starting with sounds that are similar to those in English, and we combine them.
I'm not that far (just started to learn "chicken" ;-)), but I guess that these letters were chosen as starters because with them we can form first words. So to me, the approach looks more holistic than starting by learning the letters of the Alphabet in their sequence as Alphabet.
Just my thoughts. I'm going with the flow, and I'm trusting the flow ... :-)
The course is in Beta. It was started yesterday. I expect errors and gaps to be there -- this is normal for Beta, but we need this stage to go on to finally reach a stable course.
If you find mistakes, then you should report them to the contributor team. This will help us all. :-)