How close is the light?
Your temps are about right on. Some like it to be even a bit warmer than what you have it. 27c is 80.6f. All but a perfect temp. In reality, and to a certain point. Higher light levels, require higher ambient air temperatures. And the higher the light level, the more need for fresh air supply, or CO2, and unless you have an enclosure, thats 100% air tight, and no leaks CO2 is beneficial. But in most cases, it just goes out the nearest crack, or hole, and is useless. CO2, will navigate to any area, that it can escape from.
Sometimes a large amount of resin production on the leaves, can make them taco. Not saying thats what yours are doing, but it is one thing, other than light intensity, that can cause tacoing.
It would be nice to have a photo.
I would find a way to get more air to them. Can you open the tent when lights on?? If you can, Id open the tent, and put a box fan, or some kind of fairly powerful fan outside of the tent, pointing to inside the tent. Id get air to it any way I can. Weed really only requires a few basic needs. Best to keep things simple. Weed basically needs correct medium. Proper fertilizer. Good temperature. Knowlege of how, and when to water. Supply constant fresh air supply. Give plants strong light. 7 basic needs is about all they require. Deviate from any of them, and quality, and production, will suffer.
Would really be nice to have a photo. Plus need to know how far the light is away from the top of the plants. Id raise the light, before I would dim it. Also a 600w, is really best used in a 3 x 3.
When they first came out with HID in 77-78, they always recommended a 1000w in a 4 x 4 area, and a 600w in a 3 x 3. A 1000w in a 4 x 4 is 62.5w sq/m, and the 600w is 66w sq/m. I see consumers using a 600w in a 4 x 4, but the factory, someone like Hortilux, recommends 600w in 3 x 3 and 1000w in a 4 x 4. And when Gavita came out with the 1700e, ( 645w LED ) it was recommended to replace a 1000w HID in a 4 x 4 area. 40.3w sq/ft. Will a 600w grow plants in a 4 x 4? Yes, but the best stuff, will be within the 3 x 3 area.