The issue of the almost non existence of speller to Mellel is a long sad story.
I wish to present my recent experience. The speller in Mellel is shown in the following screen shot:
https://www.dropbox.com/s/joj6mf37bqp7a ... 9.png?dl=0
But, in practice, most speller in french are almost not active and when active they are very poor.
I am working now on a [paper written Hebrew and I have translated it into French.
I need to spellcheck what I print and I found work around, a very efficient one: Using Word for Mac.
I cope and paste the article I have translated in Mellel and moving it into Word, there I give the command spelling:
https://www.dropbox.com/s/3yxejgcekfeou ... 2.png?dl=0
And it works perfectly for me. When I finish, I transfer it back into Mellel. I do not like Word, and do not work with it, even that now it support R2L writing. I like Mellel.
I pray that the redlers would create a decent speller for Mellel.