You can, if you wish to go to the trouble, replace Scrivener’s dictionaries with others in hunspell format.
If you’ve done this already, don’t read the rest…
- the replacement names must be spelled EXACTLY the same as the originals. I am not sure capitals make a difference, but an underscore instead of a dash or vice versa will break them.
- When Scrivener updates, it may replace them, so keep a copy hanging around.
And at [url][JH] Dictionaries - Portuguese - #6 by Aristoteles] are instructions for replacing, if you want further reading.