Personally, I don't really trust peds pts.
Their default is "no" when you ask if something's painful.
They want to sweep any problem under the rug. They want to avoid a procedure, inject, DME that'll make them different from peers, avoid being in trouble with parent for having an issue or injury, whatever. They tend to minimize everything.
Bottom line is to have a way lower threshold for imaging, adv imaging, treating stuff (non-invasive tx) in peds.
I do arch supports (pre fab) for most peds flat foot, but customs are seldom necessary unless near skeletal maturity or oddball foot shape.
In reality, we know that flat is often pain. Pain is often less active... which is often overweight/obese.
Adults will flat out tell you that; peds often will not.
When you look at adult flat foot, even if they say the flat foot doesn't hurt, many are overweight, many are less active than normal... makes you think, to say the least.