> The cuts are usually slightly off from where I'd ideally like them to be, I think because LosslessCut can only cut on i-frames[3], but it's a totally fair tradeoff for my use case.

There is an experimental "smart cut" mode where it re-encodes the video between your cut and the next keyframe. It will of course not be entirely lossless though

https://github.com/mifi/lossless-cut/issues/126