AS> For me as a Sysop Point of view to test a prealpha and give you feedback
 AS> would be nice to see very fast, without to download and install if there
 AS> is a new version online or not. The easy way to do this is to extend the
 AS> existing prealpha download file name by mys112a47_202108142110_l64.rar
 AS> means this release ist build on the 14th of August 2021 at 21:10 or
 AS> 09:10pm at utc timezone. 

The date is already set on the timestamp of the file within the listing, so you can already use that to accomplish what you're hoping for in a very simple way:

For example you can do:
"wget -N http://mysticbbs.com/downloads/prealpha/mys112a47_l64.rar"

And that will look at the file date and download the file if its been updated since the last time you've downloaded it.  If the filename contained the date stamp within the filename then this would not work.

... How is it possible to have a civil war?

--- Mystic BBS v1.12 A47 2021/08/08 (Windows/32)