Hi,
I think I found a bug with the reminder function.
Note that I'm not using the standard Cardo but the one for "Advanced TW users" to be found under
http://cardo.wiki/#Get%20Cardo -> "All the above Plugins in an importable file:", i.e. I used a fresh TW5 file, then imported the JSON file with all plugins needed according to the installation instructions.
After installing and just adding a New Project (and without doiing anything else), I get the following output in my project dashboard:

... which is obviously not the intended output.
Furthermore, if I then go ahead and add 2 New tasks to my Sampleproject, both set to the same Due date, and with "Reminder" ticked in each related checkbox in each of the tasks, I receive the following:

i.e., I can only see one of the reminders in my Reminders tiddler, no matter how many other tasks I set up in my project.
The same goes if I set up another project, add a task to it with a reminder: It just wil not sho up in my "Reminders" tiddler "All reminders" list.
Unfortunately, this way the whole reminder functionality becomes somewhat unusable for me ...
Happy to do further testing with my clean install file if/where needed!
Best,
Steffen