So, it looks like the 5 week calendar is not 100% reliable. I'm seeing some 30K options in the 7 day calendar that don't show up on the 5 week one. These seem to involve a combination of DL and partner metal. For example, on May 7, 2018, I see ATL-EZE-GRU (DL and G3) for 30K one-way. On May 4, I see LAX-MEX-GRU (DL and AM) also for 30K one-way. These show up on the one-week view, but not the 5 week calendar.

On another note, DL seems to have gone back to use different fare classes for different award levels (instead of them all just being "N"). I'm seeing NL class for the 40K awards to GRU/GIG. This used to be used for the second level awards. N class was used for 1st-level low awards. So this also indicates that 40K is not the new low level.