As usual I can't help but exam text barely mentioned in a comic. It's my curse.
Jason has said Joker set him up twice although canon has changed since the first time. Having Joker set Jason up wouldn't have worked in old post-crisis canon and I'm a little confused how it works now. Just to avoid more confusion if Joker's claim of "making" Jason into Robin happened or not we'll just assume it's not true. We do know that Joker knows the ID's of the bat family only they (or maybe just Bruce?) weren't aware of that until Snyder's reveal.
So wouldn't Jason suspect Joker knew if he was set up? Especially if it involved his birth mother and presumably luring him to a location? Did he figure it out after the fact he discovered Joker did know their IDs?
DITF wasn't perfect, not by any means, and it desperately needs an update. It had too many coincidences linking Batman's mission that just so happened to connect with Jason's trip to find his mom. Joker didn't even know they were around until Shelia betrayed Jason.
In RHATO #0 VOL. 1 the mother was Catherine which raises the question why she was in another country. Shelia Haywood was a doctor acting as a relief worker so how would Catherine, an addict with little to no money, get there? Why did she go there? This probably means Catherine abandoned Jason too unless she believed he was dead. Making the mom Jason dies for Catherine might have happened to simplify the story. Whether it works is still up in the air.
During Damian attacking the previous Robins he mentions Jason's mom betraying Jason. Was this still true with Catherine? Tomasi did have change the script for the Tim encounter in the same arc. Artwork showed it originally had Damian calling out Tim for trying to arrange Captain Boomerangs' death. So maybe the mom betrayal still might be consistent. It should be noted though that Lobdell did retcon another appearance Jason had in the Tomasi series. The location of Jason's death and claiming he's only returned there once before to save Roy.
RHATO #9 VOL. 2 has Jason recalling being set up and he mentions a "birth mother." If Catherine was the mother in question he would have just called her mother. The wording indicates it's back to Shelia, someone else or he was still trying to find out. Whether Shelia was involved or Joker just tricked Jason into believing his mom was in the building we don't know. The #0 issue mentions a photo being sent into the bat computer which would require major hacking skills and knowing it would be Jason who was alone in the cave.
It'd be interesting to see the lengths Joker went to kill Robin but this raises all sorts of questions. I've heard about a claim that Lobdell still has Catherine as Jason's mother although I'm not sure if it's correct since the person then brought up Nocturna as a potential mother. The way it's phrased leads me to believe the Nocturna bit was more of a hope than an either or situation. The person in question claimed they hadn't heard any updated information in some time. Luck might still play a part with Joker planning everything as he'd have to have Batman a.) In the dark about Jason's mom long enough for Jason to run away (*1) and/or b.) Split the two up long enough to murder Robin.
There's questions I'd love to see answered and the story has potential. Whoever the mother is it makes for an emotional story if she's involved. I'm not sure which version of Joker's knowledge would suit the story better. If he knows and their not aware of it he has an advantage they couldn't prepare for. Bruce's arrogance of believing Joker didn't know (as shown under Snyder) makes it even more tragic. If luck was on Joker's side it still has shades of being a little too convenient like it originally does. It does however fit Joker's mind frame of his dark humor to have the events fall into place which led to his greatest victory over Batman.
*1 Which was the case in the original story.