> after being told by a user that the page fails: "The user said that when they submit the form, they get a server error page." (Importantly noting the source of information)

Apparently, there are languages (such as Mongolian or Eastern Pomo) that "automatically" include that information into the sentence by grammatical markers of "evidentiality" (just as English always marks the tense (does/did/will do)).

See https://en.wikipedia.org/wiki/Evidentiality

Evidentials in Eastern Pomo

  Evidential type       Example verb    Gloss

  nonvisual sensory     pʰa·békʰ-ink’e  "burned" 
    [speaker felt the sensation]

  inferential           pʰa·bék-ine     "must have burned"
    [speaker saw circumstantial evidence]

  hearsay (reportative) pʰa·békʰ-·le    "burned, they say"
    [speaker is reporting what was told]

  direct knowledge      pʰa·bék-a       "burned"
    [speaker has direct evidence, probably visual]