My strategy against Calanthe engines (and most recently also Shupe) with Ardal is to get just enough ahead in R1 so that the enemy could close the Gap and push me in R2, I actually prefer giving them a somewhat easy R1, but not too easy. This gives them an impression that either my hand is too good or too bad and even though Calanthe players want long rounds, they are often way to confident in pushing round 2 which you can take advantage of. If they push you, they often blow their leader straight ahead just for the overdose of engine and if you save ardal and kill/sieze another engine you take control of the round right ahead, as they usually have to catch up with you in R1 and most often will be 1-2 cards down. From there its just one response after another, though you should prioritize some cards over others.

My special tip would be to try out Betrayal if you havent already. It's fantastic against row stacking decks such as Francesca, Foltest and to some extend Calanthe as well.

Lastly, I'd add that I'm currently at Rank 1 and perhaps the decks may differ a little from Rank to Rank, so if you were asking for Pro Rank advice for example, I may as well be barking at the wrong tree here :D My impression was you're also in ranked, though, but correct me If I'm wrong.

I've actually got a few games against Cal. recorded if I remember correctly, so if you want i can send them to you tomorrow for clarification.