Wyll being witty and amusing could be the fail here. If they think that's enough to make him charismatic, they're thinking too small. A high charisma character will also be abrasive when that gets the desired result. A high charisma character just IS someone who commands respect and attracts followers. It's attitude, behavior, confidence, social skills, everything. Not just a one trick pony being good at sweet talking. People who are witty sweet talkers but not charismatic are quite obvious, and their schtick gets old fast.
To be fair. Having high CHA and knowing how to apply that charisma to get what you want are two different things. You can have a character who's naturally fun to be around and makes friends quickly, and that'd be a clear example of a character with high Charisma. But that same character might not know how to use that to their advantage or even think of it as a strength to be levied to get what they want.
I've certainly seen players with high CHA scores who make a mess out of social encounters because they didn't apply their charisma effectively. Intimidating someone they should've persuaded, using deception when there was nothing to gain from the lie, etc.
Wyll has high charisma in the sense that he comes off as good-natured and easy to get along with. He's not necessarily supposed to be manipulative.
