Is it unusual that most of the cola tops contain clear trichs and the mid section of the flowers are milky?
Nothing unusual. Tops are usually the newer growth.
Trichome maturity happens all over at various times. I have seen milky trichomes 3 weeks into flowering. You need 2 things for maturity.
Nearly all brown pistils and milky trichomes on the flowers, not the sugar leaves.
See lots of people jump the gun and harvest too early because they see milky trichomes and think they only have a day before it goes too far. I have harvested tops off plants and let the bottom buds go for weeks longer. I set one in a corner and let it go for another 6 weeks and it only had a little amber on them.
Yes, very easy to harvest too early.
I go for 20% amber on the buds that look like the majority