The answer is No
For me, to be a Robin, your name has to be synonymous with the mantle. Whenever someone says names like Tim Drake or Carrie Kelly, you have to think Robin. Robin is part of who they are, not just their history.
For Stephanie, you just don't get that same connection. Sure, she was Robin, but Robin isn't who she is. Stephanie can easily exist and not be a completely different character without her time as Robin (as she does in current continuity). She isn't really defined by her time as Robin like the others are, and to say she is the "fourth Robin" is kind of insulting to those who actually contributed to the mantle.
To call Stephanie "one of the Robins" is like saying Dick and Gordon
are Batman just because they officially held the mantle (in continuity, no less!), and if you think "oh, he's Batman!" when you hear Dick Grayson or Commissioner Gordon, you should probably get your head checked.
I came to this forum because I wanted to confirm that everyone understood what a true Robin is, but I was hugely disappointed when I saw that 40% of voters said Stephanie is one of the Robins.
I hope this will change people's minds
PS
I just read the OP's response (i didn't before cause it looked too long
) and I realize I'm kind of just repeating his points (because he is spot on!).
But now I am extremely baffled as to how anyone can disagree with him! idk it just seems obvious that Steph's time as Robin was largely inconsequential and merely a "bump in the road" as the OP cleverly put it and in no way meant to be considered as meaningful as the true Robins' time in the mantle