I think there is a bug in the last versions of G2.
I am working on an Italic, which has been slanted extra and made more wide. I did this in UFOstretch. After importing/opening the UFO’s every runs fine.
Now I want to clean up the typeface. When I add extremes and/or Round Coordinates using the menu, nodes are not always positioned on rounded values.
I send a screenshot of one of the situations by mail.