Johnson handed Hoffmann his full debut after the 22-year-old joined on loan from Bayern Munich on deadline day.
The goalkeeper had a difficult debut as John Coleman’s side constantly applied pressure from set-piece scenarios, but the Black Cats head coach said he was encouraged by much of the youngster’s game.
"There were a couple of what I'd call rusty moments," Johnson said.
"There were a couple of aerial ones where he made bold decisions, which I like, but maybe just hasn't quite got his timing yet.
"It was a big decision and a risky one really, throwing him in.
"If he had made a mistake it would have been on me and not him, because he was playing behind two centre-halves he had never met before until the day before the game.
"But he was very good with his feet, and that played a big part in our build phase and we had two or three chances on the back of that.
"He did take two or three crosses and made one great save at the near post that was very important.
"We knew that Accrington were going to be a threat from set-plays and we are disappointed that we have conceded from one, but at the same time when it did get tricky to deal with because we hadn't managed to finish them off, we did get bodies in the way and make clearances."
Sunderland have an option to convert Hoffmann’s loan into a permanent deal at the end of the season.
Speaking on Friday Johnson admitted that Anthony Patterson, who dropped out of the squad on Saturday, could now go out on loan to the National League.
“I think that all players will get their opportunity at various points of the season, that’s for sure,” he said.
“I think Patto is a really bright young goalkeeper, I love him to bits in terms of how he makes outstanding saves. His reflexes and agility is top draw.
“I think he is probably behind the other two just in terms of his football development in terms of exposure of game time. With all our young players I really want to try to get them 25 starts.
“The minute they go beyond the 23s which you see now with Dan Neil, Patterson, Elliot Embleton, these guys are now well beyond that in terms of what they can bring. If you put them back in that it can be a bit regressive with their development.
“With Patto, we just want to try and get him those 25 games,” Johnson added.
“If that’s at Sunderland great, if it’s not at Sunderland we’ve got the option to loan him out to the conference because it protects us as we have the recall after 28 days.
“If we do that before January then we can make another decision in January based on what is right for Patto and the club.”
Johnson added: “We do see Patto as somebody who can genuinely contend for us in any division moving forward but he’s only had two or three league games.
“I think he’s going to need 40-50 before we’ve truly seen everything of Patto at whatever level.”