Perhaps this should be split into two issues, as the fix will likely be different for the two.

For the first part (SyntaxError), my initial impression is that this will require a similar fix, or extension of it, to the one in issue15110.  That fix was limited just to the execution of the module, while this problem happens earlier (during the compilation step in SourceLoader.get_code()).  

For the second part, it is all about failures during the execution of an import that was initiated during the import of another module.  That traceback is definitely less than helpful.  A better traceback would is doable.

For both (and maybe for issue15110) we should explore using exception chaining to separate the import portion from the rest.  I see about working on a patch later this evening.