Thanks for your suggestions @pisum . This one could be very useful, :
?updated_since=[last time you ran your report]
For the others, you are presuming things that are not true: no common taxa, no common place. Not even shared taxonomic expertise (are you presuming they are taxonomists? I didn’t say that, at least for the 2nd example use case in my original post).
As I said we are just looking for words in comments about any taxa (in certain languages -that’s their expertise-, but once we got the comments it’s very easy to filter those languages of our interest).
It’s just a matter of taking profit of iNaturalist collateral data (comments) for something which is pretty unrelatd to iNaturalist common use cases.
But as I said, such a feature could be very useful for other common use cases, like searching for users’ mentions as I exposed in the above example (which applies as well to my use case, but also to many other possible scenarios).