I purchased an apartment a year ago in Nuevo Horizonte .The windows were pitted with 10 years of blown sand.I tried many chemicals and solutions to get rid of these marks but nothing worked.
Then I had a brain wave and used a new,wet ,brillo pad ,first on an area that would not have shown if the glass was scratched and then on all the patio doors glass.
This was amazing how easily the glass came up like new.
After this treatment I polished the glass.
Let me know how you get on.
PS Work the pad in circular motions.
My glass table was looking very sorry for itself (cigarette burns etc); I bought a cerium oxide polishing kit from amazon/ebay. There's loads there.
You mix up some powder with water into a slurry and use a pad on an electric drill. It worked brilliantly, the glass is gleaming now.
Check out Youtube for 'glass polishing cerium oxide' for demonstrations.