Any error detection is better than none.
if you know your minikey's bitcoin address you'll know if there was an error typing in your minikey. so you dont need error detection in that case. if you dont know your bitcoin address then you might be in trouble. even with this "error detection"
A 22-character mini-key has 115 bits of entropy, which is pretty secure for now.
and 30-character ones are just as secure as a full bitcoin private key.