Thank you for the images because they reveal that the missing leaf tissue in the first 2 pictures are due to insects.
The damage to the single leaf with neatly 25% missing is due to feeding by a caterpillar whereas most of the damage on the 3 leaves is due to root weevils.
The good news, though, is that both kinds of damage occurred quite a while ago.. The reason? The edge of the holes is dry and gray. If this damage was on-going, the edge of the wound would be green and moist.
Unfortunately, root weevil larvae (youngsters) live in the soil. Thus, some may be in the potting mix. Don't disturb the potting mix to look for them; instead, keep an eye out for fresh damage along about May or later. when the adults will be active.
Obvious damage by spider mites is shown in the final image - the bleached leaves with minimal green remaining. Please keep these leaves until they naturally drop because, even though you may consider them ugly, they do have some green on them which will help support the plant until it again goes outdoors.
Keep a watch on the trees, especially while they are still indoors, becasue the mites are likely to build up to damaging populations again. The first indication will be a faint webbing on the underside of a leaf, or multiple, leaves. The sooner you recognize an infestation, then act, the better.
When you see the signs of mites, take the plant outdoors on a mild day and thoroughly spritz off the leaves by aiming at the undersides. Repeat as needed.
If you think you need stronger treatment, spray the leaf undersides with insecticidal soap, diluted according to label directions. Reserve neem for other, more troublesome, problems.
I see that you have the trees very close to a window as that's generally beneficial for citrus. But, be aware that, if the temperatures is predicted for freezing or worse, move the trees away from the window until temperatures rise to safe levels. (Yes, subtropical plants such as citrus can be damaged during a cold night when they are close to a window.)
I have mixed thoughts about the dish with water sitting on the heat register in the floor. Citrus can survive without the extra humidity but they will suffer if they also receive blasts of heat from the furnace.
If you have other questions, please ask when you reply to this email.