have dolors demon powers been retconned?

[Sylphe]

Then again, what Hendricksen did was an inpromptu transformation without a test run. He said he would've liked to study more before doing this but it was do or die.

When Hendrickson said that, he was referring to the Gray Demon, which he doesn't have enough time to study in detail ! But for the case of the Red Demon, i think Hendy was in complete control over the demonic abilities he gained from it and had had plenty of time to experiment on ! ( after all, the RD corpse was found 20 years ago prior to the events of the manga)
For the fact that Dolor and Gloxinia not being able to use demon regen', i think it's most likely because their demonization was the same as the reactors type HKs ( aka the New Generation)

 

[Nait Sirhc]

Wouldn't Hendy's demonization be the same as the reactors? He drank/mainlined/whatever the demon blood too. Glox and Dolor had a lot more than 20 years to experiment with demonic powers, so it seems like they'd be very familiar.

Although it could be that this is the first time they've ever been injured since becoming demons.