I've only done Syntax out of those three (and this was a few years ago, so maybe someone else can jump in with a more recent update). This was back when Peter Hurst took the subject, but his approach was to just take attendence on two random days throughout semester. However, he was pretty chill about adding your name to the 'attended' list if you were keeping up to date with lecture recordings and messaged him within a day or two. It was mostly just to disincentivise people from not showing up and trying to cram all the lectures before the exam, as Syntax is one of the trickier Linguistics subjects (but is super rewarding!)
From the handbook it looks like Lesley Stirling is taking it this year, and she's an absolute gem! (She, Peter, and Brett Baker are all A+ coordinators imo, though the whole Linguistics department is great, and I'm sure there are some fresh faces now too). Lesley never took attendence in the classes I had her for, but a lot of this would be up to the uni given COVID restrictions (e.g. I wouldn't be surprised if
all lecturers were told to 'take attendence' online, even if it's not a 10% contribution or anything).
Your best bet would be to email those coordinators and ask what their plans are. Explain your situation, and I'm sure they'll be completely understanding. You could even suggest an arrangement where you're able to watch a rerun within 1-2 days and email them to be included on the roll, if needed.
It's a tough time for everyone at uni - students and lecturers, but I hope it works out for you! (And hope you have a wonderful linguistic semester
)