Personally I feel that what Reddit has been using for nearly 20 years was successful because it worked, the negativity that inevitably comes with large groups of people was the only issue and a lot of Lemmy users think it's the basic systems that worked.
Karma added a little boost to activity and engagement, while upvote/downvote helped curate content at a site wide level.
The value of these made up points is directly correlated with the size of the overall group and the larger Lemmy grows, the more it will have the same issues, it's just a matter of how long we get to enjoy this environment before it outgrows us etc.
The only important thing is that while we still can, we try to reinforce to people that the vote itself is matter of quality and appropriateness to the community the comment/post is in, as apposed to whether the thing is liked etc.
Yes. However you can install a PWA (progressive web app) via chrome and firefox (perhaps other browsers but those are the ones I use). The PWA allows you to use lemmy when logged into your instance of choice and it acts like a mobile app. To install, go yo your instance in a browser, then check our options. For chrome, it says add to home screen. I believe firefox it says install app.
I havent looked at code, so i can only guess. Just before you looked at it, i clicked downvote. I realise my mistake and unclick/click it again. The local server we're browsing on (Server A) sends the downvote to the server the post was made on(Server B), but it also temporarily adjusts it local figure for a while until it can refresh from the server the post was made on. Last it knew server B had a tally at 0 downvotes, so it goes negative. (If Server A had a downvote figure of 4, the same process would have shown 3 to you)
It registered, I see the downvote. The reason you don't see downvotes on most comments is that most people here don't give them out for no reason, so there just aren't any to display.
Pretty sure the negative downvotes weren't intentional manipulation, my best guess was some cross-federation code interacting weirdly. Though it's fixed now anyway, you responded to a comment that was 17 days old.