HolyGambler
Author, bro. You can just make a separate chapter in which there will be a description of the technicians, and not mess with the chapter with this information. Take him out into the world, let him run around and fight his strong opponents. With Chinese cultivators, asami, spirits with ancient mummies, magicians, vampires let him beat. Fairies will meet, different monsters of ancient Greece. There are plenty of options, so the story will be more interesting.
Well the innovative ideas for proper ki cultivation are amazing including but not limited to some of the types of techniques like way to aquire god ki by yourself or the true nature of spirit control. Instead of flashbacks and timeskips wouldn't it be better to make side stories with future segments (showing clips from what will happen in post canon dxd) with hints of possible changes due to his presence (between the training arc) so that it doesn't get bland and too informative.
I have mixed feelings about all the information from the powers that be. First, I think it is extremely necessary, despite it being a lot of information, it doesn't seem like a simple random dump, you can read it and understand it calmly, that pleases me a lot, but on the other hand, the biggest problem is that the story doesn't progress, I like it of this information, but it feels more like you're reading a prequel to the story, enjoying it, but eager to jump straight in. The best solution would be to release all these chapters at once and then start the story, that way we could read everything and then focus on the main story, you could even put a prefix on the "prequel" chapters so that those who don't like it can just skip. the problem with this is that you probably shouldn't have chapters ready to post at once and if I have to choose, I'd prefer you keep it as it currently is. like I said, my thoughts on this story are contradictory, I like how it's going, but there's also a certain acceptable limit to chapter information before the story becomes a textbook. For now it's completely acceptable what you're doing, thanks for this story by the way.