A non-reciprocating charging handle does not solve the problem of hitting your knuckles on a fat sight like an Eotech. That's what these offset charging handles are for.
Instead it's more for silencing critics like this that refuse to get off the AR.
AR-18 Bolt Carrier
G36 Bolt Carrier
SCAR Bolt Carrier
Make a new short carrier group and use the space where the armature used to be for the mechanism. To mount the replacement armature in place, use those 3 long holes near the side rails or connect it to the upper or lower rail.
Yes, I know. There might need to be some tuning because less mass is being thrown about. More parts means more complicated. Reliability will be affected. Durability of the parts may be in question. The non-reciprocating bolt will need some sort of forward assist... Point is, it's possible to make it without drastically altering the receiver.
If you make the charging handle non-reciprocating, it also makes it possible for a charging handle to be moved around to the back for those that refuse to accept change. The last time I saw a "fix" to make the SCAR charge like an AR it was a piece of string threaded from the charging handle's hole to the rear sight with a small loop in it for you to put your finger in. The string was flexible enough that it would droop when the bolt was cycling so it would not hit him in the face... much. Then when he wanted to charge the weapon he pulled the string taut and he had his horrible solution to an overblown problem.