If you want to keep the chunks, maybe just add more of the pineapple puree so you're adding enough liquid and see what happens. 240g?
Also, is your puree raw? If so, that may be part of why it takes so long to cook. Try bringing your chunky puree to a boil to start breaking down all the cells and releasing all the juices instead of waiting for that to happen in the caramel. I haven't cooked with pineapple in a while, but I vaguely recall caramelizing the fresh fruit for a dessert in the past. Despite how fibrous pineapple seems, it is quite juicy and cooks down a lot once you add heat and sugar.
