The only people who work on any sort of Perfherder backend logic is the Perf developers. It's unclear to me what the issue is. If the issue is that you don't have jobs for those alerts that's because we expire jobs that are older than 4 months. If the issue relates to the logic that is generating alerts, that should be something your team looks into.
Bug 1616019 Comment 8 Edit History
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The issue is that alerts from 4 months ago are missing job data, correct? We expire jobs for any jobs older than 4 months but if we were somehow prematurely expiring data job data this would affect all of Treeherder so this sounds like something very specific to Perfherder backend logic. Since the only people who work on Perfherder is the Perf developers it'd be preferable to only pull someone in from the Treeherder team to help after investigating and determining it was a change we made that has caused the problem.