I got an email from Chris at HQ yesterday. They have updated the Guidelines with two new paragraphs.
The 9. Time-Limited section has been amended to note that is acceptable for challenges to require finding some number of caches per day of week, provided the number is cumulative over all years. Example, find 100 caches on Mondays.
The 10. Source of Criteria section has been amended to note that is it not acceptable for challenges to restrict finds to caches published prior to a particular date. Example, find 100 Wherigo caches published prior to 11/21/2019. However, we do not want for this guidance to inadvertently affect Jasmer challenges, so we have also specified in 10. Source of Criteria that Jasmer challenges and variations are acceptable.