Is certainty a requirement for truth? We know that certainty is not a requirement for knowledge, but how about for truth?

No; truth doesn't require certainty. Whether something is true is a matter of how things are, whether anyone is certain about it or even aware of it. For example: I have a file cabinet in my office with some papers in it. No one (certainly not me) is certain exactly how many pieces of paper are in the cabinet, though there's a truth of the matter. The truth is determined simply by what's in the cabinet, whether anyone knows or bothers to check.

In the case of my file cabinet, it's at least possible to find out how many pieces of paper are in it, and so someone might suggest modifying the view you're asking about. Perhaps there's a truth about a matter only if it's at least possible for someone to become certain of it. And indeed, people have defended views like that. They go under the umbrella of verificationism. There are even some cases where something like verificationism is plausible. For example: we don't believe there's such a thing as absolute uniform (inertial) motion because our physics tells us that even in principle we couldn't detect it. On the other hand, it's hard to see how anyone could ever be certain of exactly how many dinosaurs were alive on earth exactly 100 million years before midnite, New Years 2018, GMT. Nonetheless, the fact that we have no way of being certain doesn't seem to have anything to do with whether or not there's a truth of the matter. In the case of absolute motion, questions of verifiability shade over into questions of what we would even mean by "absolute inertial motion." For the dinosaurs, the fact that there's no way for us to be certain of the number doesn't seem to have anything to do with meaning.

Here's a quicker way to the point: you agree that knowledge doesn't require certainty. But if we can know things we're not certain of, then there are truths we can know without being certain. That's a way of getting to the same place from a premise you've already granted.

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