Ok! That's so good that they are fewer than 6 weeks in.
I would love to hear how they study, and maybe what time of day they do the exercises. Everything gets easier around 6 weeks of habit training.
If they aren't using the skinny book, that will help a lot, be sure they're speaking the words as hey write them down, and perhaps simply push play on the vocab lab once more, just to sit back and listen, or even doodle while they listen and repeat.
I'll bet if they give the words just three more minutes per day (one more reading, or a doodle, or an action) they'll see their memory ability double.
Flashcards are also ALWAYS a good thing - the smaller the better. Here's my favorite type: https://amzn.to/4gFkxEp
The schedule itself is 100% customizable. Give them more time to complete a lesson for the next couple of weeks. It's much better to get 100% mastery (or 80%) than to be "on time" and not have confidence in what you've learned. There are only 25 lessons for the school year so that no one has to rush. Hope this helps!