I haven't used Brewferm, but that sounds like a high FG. Did you just pitch the dry yeast, or did you make a starter? For a tripel, you want the FG to be very low and finish relatively dry. I would try to agitate it a bit by shaking it lightly every few hours and let it sit for another week. Your temperature range sounds about right, but (from the experience I have from the tripel yeast I use) you want it to be closer to 22C.
I can't comment on the caramelized sugars, because there are far too many variables, such as how much you cooked, if you burned it, if you added it during the boil, if you added it to the fermenter, etc. Generally speaking, thicker sugars will lengthen the fermentation process but again there's a lot to consider, and I think that after 2 weeks it's more likely that you just under-pitched and the yeast is just chugging along slowly.