Congratulations to your friend for receiving a term sheet. The tech press has conditioned us that raising money is easy, while the reality for most is raising money at such a young stage is hard. Vast majority of startups don't get into YC or Angelpad. The primary value at this stage is external validation from a real investor. If they are a real investor with a network their primary value is helping you get to that next level with follow on fundraising. Quibbling over a point or two here is missing the big point. If you fail it's meaningless, if you're really successful you won't miss it.
Agree that like any savvy entrepreneur, your friend should attempt to get more capital and/or reduce the percentage. Depends on the team, idea, how long he has been at it. It's only a bad offer if he can get a materially better one. The market is efficient like that. What's your friend's BATNA - best alternative to no agreement? If he doesn't need the money then he can wait and shop around. If he really needs the capital there isn't much choice.
Terms wise I would advise your friend to keep it clean. If the investors want to be fully aligned with the founders, they should be right there as common with no special anti-dilution provisions. If they want preferred treatment then just do a convertible note with a cap so that they are guaranteed the 8% conversion to preferred and the associated rights if a qualifying financing is reached.