We have similar demands, and we solve it in the following:

We use a run database. In the simplest case, this can be a text file which gets written at the end of the file. The 
mlogger has a built in SQL interface, so one can keep that table even inside a SQL interface. The per-run-
information then contains the run number, start/stop time, number of events, some run parameters and a "junk" 
flag. So if a run has a problem, one can set the junk flag by accessing the database (or text file) and setting this 
flag. In many cases you see that a run had a problem not at the end of the run, but a bit later. You mayby realize 
that the last two or three runs had the problem. With the run database approach, you can flag any run as "junk" 
later, which we need often, An edit-on-end would not make this possible.

So technically putting and edit-on-end is not a problem, but your life might be much easier if you use a run 
database as outlined above.

Best regards,
Stefan