Re: standing water`
Do you have the moonroof?
It's not uncommon for the drain tubes to clog, and then from water to enter through the passenger or driver A-Pillar.
You should certainly be able to tell if it is coolant, as mentioned before...though it should be orange not green if you are using the correct HOAT stuff.
The windshield seal could also leak and result in water in that area, though this is far less common than the moonroof.