If your goal is to understand everything, what you might want to do is transcribe it into a Google Doc. I’ve done that with a few books. I’ll type the whole thing down, read it once myself, then copy-paste it into DeepL to check my own work. But that’ll tremendously slow you down, so I don’t recommend it unless you’re using it to, like, update a Fandom wiki or something.
If you find yourself looking words up repeatedly, you might want to make a mini-vocab list, so you can glance at one document rather than type the same thing into a dictionary over and over. As a rule, I add words if I look them up more than once.
If you’d like examples, I’ve been reading Japanese math books and my Google doc for that is here (perhaps counterintuitively, I’ve found technical documents are actually the easiest thing to read in another language; fiction is way harder). I’ve also been reading Xenogears Perfect Works and here’s the vocab list I just started on the other day. Good luck!