That’s kinda weird. The only one who consistently seems to forget is Ashley. The others have a better time remembering. Travis, Marisha, and Liam seem mostly on top of things. Laura has moments of utter brilliance with her spells. Sam and Taliesin seem a bit in between.
I want to preface this by saying I respect all of them. For being a great example of friends getting together and playing RPGs, for consistently standing by their morals and sponsoring charities, for showcasing frustrations many of us have to deal with in our lives, etc. They have done a tremendous amount for the community, for the future of the hobby, and just for general acceptance of "nerds" compared to the 80s and 90s.
So, with that out of the way. I honestly think most of them perform at a lower mechanical level than they should be at this point (certainly lower than my own players). Ashley has the most issues - it's a good day when she remembers to reckless attack, a great day when she remembers her Aasimar form deals bonus damage, and she promptly forgot the whole tutorial Matt ran for her about deathless frenzy. I'm honestly not sure why she has so much trouble, when she's clearly a really bright person (and funny as heck).
Liam has really improved! He used to struggle to remember how sneak attack worked, but since he started running 5E games for his family, he's really done a great job learning the rules and being the kind of player I would want at my own table.
Sam has gone the opposite way. He actually knew his stuff when he was playing Scanlan. He didn't know much about non-bard things, but that was fine, because he knew bards. Rogues? Not so much. He has to be reminded about sneak attack almost as much as Vax did, and he barely remembers he's wearing an Elven Cloak, gets advantage on spells when he hides, etc.
Marisha was famously bad as Keyleth, but feels much more at home playing a class like Monk. Enough options that she can get creative with them and do a good job, while avoiding the craziness of another primary caster. I would like to see her play another caster long-term to see how much she has improved, but I'm also wary because I wouldn't want to get stuck with another Keyleth.
Travis and Laura are not at Liam's level, but they do decent. They forget often enough that it's frustrating to listen to, but not as much as some of the biggest offenders. I would expect players with their level of experience to be performing at Liam's level at this point, though. All of them have pulled off some glorious moments regardless.
The biggest thing they struggle with is Analysis Paralysis. They struggled with it in Campaign 1, but Campaign 2 took it to a whole new level. I look forward to seeing if Campaign 3 takes any steps to mitigate this the way they mitigated shopping episodes in Campaign 2.