I'm not really sure how to do that, but I'll try:
:hr:Special:Contributions/93.137.7.71
I wish to hide the last two edits of this user (edits 5638722 [page Nikola Kopernik] and 5638723 [page Ražanj (Rogoznica)] ).
The script sends the following params to the API:

action: "revisiondelete"
format: "json"
hide: "content"
ids: "5638722|5638723"
reason: "grafit"
token: "a6c0bdbe65d6b5fddfa977442eae45695f7c7c58+\"
type: "revision"

API responds with:

{
  "revisiondelete": {
    "status": "Success",
    "target": "Nikola Kopernik",
    "items": [
      {
        "status": "Success",
        "id": 5638722,
        "timestamp": "2020-10-02T22:26:34Z",
        "texthidden": "",
        "userid": 0,
        "user": "93.137.7.71",
        "comment": ""
      },
      {
        "status": "Fail",
        "errors": [
          {
            "message": "revdelete-modify-missing",
            "params": [
              5638723
            ],
            "code": "revdelete-modify-missing",
            "type": "error"
          }
        ],
        "warnings": [],
        "id": 5638723
      }
    ]
  }
}

The first edit is hidden, the second one returns an error.
Thanks!

Some more info: the API looks at the first ID, finds the matching page, and assigns the target parameter automatically. It then looks at the second ID, cannot find the second revision ID on the target page history (because the second ID belongs to a different page), and throws an error.

This is not intended behaviour because I never assigned the target parameter.

The API should limit itself to searching revisions of a single page only if the target parameter was set in the initial request. Otherwise, it should allow hiding multiple revisions of multiple pages.