The word ‘ironic’ is known to be quite frequently misused, to the point that some dictionaries have actually started accepting the de facto usage as another definition, usually calling it situational irony.
Is there a better, more appropriate term for this construct?
You seem resistant to the idea that situational irony itself is the most appropriate term for the concept. In fact, it has been recognized as a form of irony since the eighteenth century, and the term "situational irony" has been around for decades (here are two citations from 1960). There's nothing improper about it at all.
The things that are incorrectly ascribed to irony fall into a few categories. Some are coincidence:
Ironically, I ended up in the same store as my mother.
Sometimes it's just bad luck:
I hate cats and ironically, my new girlfriend has seven.
And a more extreme example is just tragedy:
I was always afraid of getting cancer, then ironically I had a stroke.
:-|