Sure. They were linked in the app too btw. Not every language does have one so maybe that's why you didn't find them.
I found out about it only yesterday so I can't really answer you this but it really seems like english works really well. I can't day of it worked like tie with the old dictionary. Maybe someone else can answer this as I would like to know this as well.
Using it since version 14.1, as far as I remember but since then, I was finally able to replace gboard. Heli is really awesome. I always believed that florisboard will be my gboard replacement but for non-english swipe users nothing really changed or improved for years and then heli came out of the blue. Of course, it's still a compromise compared to gboard and it probably always will be but to me it reached a point where this is minimal.
Yesterday I found out about the experimental dictionaries and imported them. Let's see if there will be visible improvement. Does anyone have more experience with those dictionaries?
I use pdfarranger, it can do everything I need. Not sure it can do everything you need so it's best to just test it. Not sure it can compress for example.