reducing sugar

I don't know baking like Boulangere does but I am thinking maybe palm sugar would work - it's not as sweet as standard white sugar so you could use the same amopunt and reduce the sweetness ...

Again, I'd suggest honey. It is an invert sugar, meaning one in solution, so it's perception on your palate is going to be different. I should add that, being an invert sugar, it contains a small amount of acid which keeps it in solution, as opposed to reverting to a crystalline state. For every 8 ounces of honey you use, you should also add 1/2 teaspoon of baking soda to neutralize the acid.

Thanks. Actually, it's the overly sweet TASTE that I want to change. What's a substitute that tastes less sweet but does the job (rise and browning)?

It will affect the degree to which whatever you are baking browns. It may also affect the rise, since with cookies at least, the first step of creaming the butter & sugar together creates tiny pockets of air which expand in the presence of heat, helping with the rise. You can replace with honey, which is twice as sweet at sugar, so for 7 ounces of sugar (one level cup), substitute 3.5 fluid ounces of honey.