I wish I could recommend this
It teaches you to identify the names of the letters but I’m doubtful it would help you read or write. The quiz should be to hear the sound and write the letter. That would be doable with the technology already in the app. Some apps will match your spoken words to a native audio file which requires machine learning, so I understand this app would most likely not have access to that technology. However, they could provide words for you to try and read, and then play the word read correctly for you to check yourself against. Another possibility would be to provide phonetic readings of words like Sesame Street (“c,” “at” — “cat” etc). That being said, this is the best Yiddish app I’ve tried so far! It’s sad and disappointing but not unexpected that resources to learn Yiddish are so few.