them be sugars. you wants them gone anyway.
this is why you need in house analytics when you can test the “WTF is this” and confirm it’s not your target cannabinoid, you can figure out what’s going on waaay faster.
see if you can turn them to taffy and pull them in the rotoflask. Id try dropping to 60C or maybe even 30C without rotation when you’re almost done. to see if you can get them to separate out and maybe stick. pull them (hook?) . then take the temp back up to finish decarb. I don’t know if the MCT is a requirement. I don’t think so. the longer you cook them, the easier they semm to be to separate.
you can also let them caramelize then char. 'cept the burnt taste lingers (I’ve not tried distilling the burnt taste out, that should work). you want to ditch as much ballast as possible before hitting the boiling flask. to avoid as many side reactions as possible.
yeah you went from 2.5l to 1.75l & it took forever, because you still had more than 20% ethanol in there when you started counting. 
edit: the MCT might be important. at least for lowering the viscosity enough to enable pour off of the target fraction. these days I pull it after the crude has been homogenized into MCT at final retail strength. it sticks to the sides & bottom of the kegs which are cooled to encourage this.