Hi lornatrae, I was discussing this with a member today. Urine can range from yellow to orange to red. A pale yellow colour urine will turn to a reddish colour once it’s exposed to the air for a while. Also, some veggies can colour the urine.
With the litter training, I would opt to put down some non absorbent flooring, like a peice of vinyl. That way, if they pee out of the box, you can soak it up with paper towel and then put that in the box. Then hopefully, they learn where it is supposed to go. Sometimes, with absorbant materials as flooring, they’ll use it as it take the moisture away and they remain clean (which is what they want!). So they may find it a convenient toilet.
The hay is a good litter training tool. They do like to eat it and toilet simultaneously so try putting the hay in one end of the litter box or a feeder suspended over it. Maybe even designate this as the only place for hay until their litter box habits have cemented in.