Would the 10-year-old be expected to go through school again? If you had enough childhood experience/expectations forced upon you, it may begin to overwrite some of the memories (if you're treated in a certain way, then you begin to act accordingly).
Also, if you're in a pre-pubescent body, hormonal changes haven't yet happened, so reconciling sexual desires and complex emotional relationships simply may not tally with the chemical and neurological structure of a young child. Perhaps some kind of preservation instinct would kick in - the brain may try to categorise the memories as some kind of distant dream in order to avoid emotional trauma.
But I imagine that this 10-year-old would have to grow up very quickly in order to process more fully the kind of experiences their 50-year-old self had - and may not recover so well. Then again, if your society is used to doing this (e.g. there are counselling sessions that go hand-in-hand with this age-reversal treatment), it's possible that people are conditioned enough to expect some kind of psychological dysphoria that this gets treated in a similar way.
If a 50-year-old gets put back into their pre-pubescent body, they may become quite uncoordinated for a short time. Children adapt very quickly (and adults are still surprisingly fast!), so they'd probably get better very soon, but changes in height, weight, strength, limb ratio, strength-to-weight ratio, etc. could be confusing for a while.
Are different laws in place for those who have age-reversal treatment? Would a recently-remade 20-year-old have to pay car insurance premiums for a normal 20-y-o, or would no claims discount carry over? Would your 10-year-old be treated like a minor in the eyes of the law, or like a adult? Could they see adult films, listen to parental advisory lyrics, need a chaperone at a theme park, be allowed to drive?
I imagine it would be a bit of a shock to see a child behind the wheel of a Ferrari, but I suppose they could have certificates proving their reversed-age identity. But this may also end up with other children/teenagers trying to get away with stuff by faking ID that shows they had age-reversal treatment.