Thanks mekkablue. I really appreciate your help. Trying to design a font when you’re not a prfessional type designer can be a really be a lonely labor…
So I took a closer look at a few letters with red nodes, and all of them had points that were too close to each other.
I cleaned up the path of a few glyphs on my original illustrator file, made some minor changes and add it to Fontself, then exported to OTF… and Glyphs Mini can’t open my file again ! 
See my other post >
https://forum.glyphsapp.com/t/cant-open-an-otf-file-exported-from-fontself/16080/2
The only difference is about the numbers that have changed :
(***-[NSArray subarrayWithRange:] range {0, 256} extends beyond bounds [0 … 254])
Do you know what could I do ?