Inquiringmind wrote:
OK, so if I understand correctly, I should remove a bulb, get up there
with a flashlight and see if the inside of the can says what it is
rated for?

Yes, there should be a very clear label that states the types of bulbs
allowed. It might include variations of the fixture because many
recessed lights are sold in two parts, the "can" and the "trim". If the
label is on the can then it has to list all possible trims.

How would I check whether the yellowing is due to wiring issues?

Thanks!

Test the voltage, anything below 100V is definitely too low!
(If you don't know how or have the tester then hire it out! Home
electrical accidents are very common these days.)

RickR