WANT TO USE THE WORD IF

This is a sentence, or part of a sentence, from one of my favorite books: "… the one last place where a renewed, post-seizure, on-the-diagnostic-upswing if still slightly shaky young gender-dysphoric might yet expect a bit of kindness"

Now I want to focus on the "if still slightly shaky" part. I'd like to use the "if" in a similar fashion. That quote was just the best example I could find.

Now my sentence goes something like "I have this illogical if beneficial long-term unwillingness to spend any money."

It's talking about how my cheapness doesn't make any sense but might be of benefit long-term because, well, then I save the money.

My question would be is there a better phrase I could use than "beneficial long-term" there? I can't think of a better way to say that.

Then also: Does it matter that the writer of my example sentence added in the "if still slightly shaky" to convey something negative while my "if beneficial long-term" adds in something positive? Am I therefore using it wrong?

And one more: Although unconventional, I understand the writer's omission of a comma there. But in my case, I'm leaning towards one. I don't know. What do you think?

And thank you. I appreciate the help.