Here are my two cents as an outsider looking in. I spend ~15-30 mins a day on Lemmy (usually while doing other things), so I see a decent amount of content but I am not at the leading edge of posts. When I look at posts, I rarely, if ever see spam. For the most part there is civil conversations and those that attempt to derail them are downvoted and, in some cases, banned.
Does this mean that moderation isn't a problem? No, I am but one user. However, it does indicate it is not a chronic issue. Personally I would like to see you guys refederate, as that could only increase the quality of discussions throughout the fediverse.