Some quick thoughts:

1. There is no way to say that I think the problem is not big/neglected/solvable. Hence ratings provide little information. It could be that only 1 in 10 people think that a problem is solvable, but if enough people think about voting on the cause, it will have a higher solvability rating than a problem that is in a less prominent place within the website. And if you sort problems by "most attention required", then problems that received most votes initially will continue receiving more votes. Instead of a checkbox, I would put a slider so we could vote how solvable a problem is.

2. People who know very little about problems can vote, and their votes will weight the same as people who know a lot about arguments for and against the issue. If someone mentions the website in some animal discussion group, you might get many people voting favourably for animal causes and skew the results. Hence, as it is, it's currently more of a popularity contest rather than something that could be helpful prioritise. And the EA survey might be better for gauging popularity of various causes.

3. Scale-neglectedness-solvability framework needs to be applied with care and not all the readers will do that. Maybe a different phrasing of questions would help. E.g. instead of "think this is a solvable problem" you could have something like "if we doubled the resources dedicated to solving this problem, what fraction of the problem would we expect to solve?" (taken from here). Also, it's unclear whether this is the best framework for prioritizing causes, it's been criticised. And we already have ratings for scale-neglectedness-tractability at the 80,000 hours website, I'm not sure this will give more accurate ratings.

I like how the website looks, how it's organized, and how fast it is though. I think that it could be a good idea to have a website for cause prioritization discussions. Although I think there would be a big chance that it wouldn't become popular, even if you do it well. One way to make such website that I imagine could maybe be useful is if you could post various arguments for and against a cause area, and other people could upvote/downvote/comment on these arguments, or propose different ways to phrase them. I remember that a couple of years ago some Scandinavian EA wanted to make a platform that was similar to this but I can't find it now.

Also, in case you didn't know, there are two wikis about cause prioritisation: http://priority.wiki/ and https://causeprioritization.org/ Maybe information in them could be used in some way.

Cool idea!

A few things I just noticed:

1. It would be nice if the reordering happened only on reload and not immediately. I sometimes ticked an “importance” box fully intent to also tick another one, but then the block jumped away, and I’d have to go looking for it again.
2. I second Saulius’s feedback: I also feel like it’d be easier for me to rate things on a three- or five-point scale or even with a slider. As it is, I’m tempted to tick almost all the boxes on all problems.
3. I really like your initial selection. I had a hard time voting on animal welfare because my assessments of farmed and wild animal welfare are so different. Then I noticed that you had anticipated my problem and added the subsections!
4. The term tractable seems more intuitive to me than solvable, since the second can be misunderstood as whether the problem can be fully solved as opposed to the definition that Saulius cites.
5. I’d like to make a distinction (and maybe a granular one) between whether I think a problem is not important/neglected/tractable or whether I have no opinion on it. E.g., I currently don’t know whether the Pain Gap is tractably addressable, but not ticking the box feels as if I were saying that it’s not tractable.
6. Not showing other people’s ratings could help avoid anchoring people.