As I am in a non English country and have to deal with at least 3 different languages I use the US-International-PC keyboard, And under OSX if you try to enter a string containing any composed character the Editor crash! (just typing " crash it)!
Thanks for bringing this bug to our attention. I was able to reproduce the crash using the information you provided and have submitted the following bug report: JIRA[UE-20079]
When this issue has been addressed, we will let you know by updating this post.
This bug has been reported fixed for the soon to be released 4.9 version of the engine. If you are still experiencing this issue at that time, please let us know by responding to this post.
Thanks again for reporting this.