I like the readability of your solution, but I believe its a waste of processing power to continue any further if the code itself is not valid.

I just tried to submit my solution again, and found it passed! Maybe a connection problem before. Thanks for the reminder about spoiler.

And when it gives a fail/error message, no other useful information was provided.

This sounds like a submission timeout. Could you add the actual error message? If there is none, it's likely a codewars issue and not a kata specific issue. (Also, please mark comments that contain solution related information as spoiler).

Great, do you have some insights how it is flawed? Don't forget to add the language where it's flawed (probably C#, right? Last time I've checked JS/Ruby/Haskell where allright). (Hint mark your comment as "issue" if it's one. Issues/suggestions and questions can be filtered and usually get more attention)

This kata is flawed!

the expected and actual are the wrong way round in the assert. this gives an incorrect error message

Random Tests are non deterministic, so should never be a part of a repeatable test set.
If you create random tests, the very least it should show is why it fails.
The reason it failed for me is that I was following the instructions for a string format of "MMMM d, yyyy", but the random tests had a date format of "MMMM d yyyy", i.e. the comma was missing. It was only by deviating from the instructions that the tests would pass.