Is it worth pulling 16 more times to get dossier after already getting Laevatain?

It's always worth it. 60 is the highest ROI value breakpoint on the banners. Especially since you already have Leav you can just hit 60 and stop. Worst case scenario that's free 10 pity towards your next 6 star drop. Best case scenario it's a free 6 star on Gilberta banner. Either way by going to 60 here and stopping you get 20 effective pulls and 10 effective pity for the 60 pulls you spent. Even if you don't want Gilberta, it's still 10 pulls 10 pity 10 chances at another 6 star, for free.