I personly would not trust that supplement at all. And are you using a supplement that has D3 in it for every feeding?!?? I use, and have used for 10 years, Repcal with out D3 for every dusting with the D3 mix every so often. I also mix in multivitamins every so often to. But i would never use the tetra product for these guys, or any reptile. Just my 2 cents.
Previously I was dusting feeders, alternating rep cal with D3 and rep cal herptivite. Now I am dusting feeders each time with Repashy Calcium Plus. Health seems the same, I'll see about breeding success in the next few months.
I've used Reptical with and without D3 in the past and so far I haven't seen any bad health effects from either one. I don't bother dusting feeders anymore since I use mealies. Instead, I just keep a bottle cap full of the supplement in the tank at all times for the geckos. When they need it, they'll lap it up like it's candy. I've had geckos essentially snub dusted crickets before, but they've always lapped up the calcium on their own. Maybe you could feed crickets/feeders straight and just keep the calcium available at all times?