There are two questions that need to be unpacked from what you've written. One -- the language - has been addressed in the linked question. The other is this: what writing system did these archeologists find this 3000-year-old language written in?
There are four known writing systems from 1000 BC we can expect an archeologist to recognize, & perhaps even understand. (Actually five, if we include written Chinese.) They are Egyptian hieroglyphs, Luwian hieroglyphs (used in parts of Anatolia), cuneiform, & the Phoenician alphabet. (The Mycenaean Linear scripts fell out of use by 1000 BC.) I don't know of any examples of the Egyptian or Luwian systems being used beyond their territories, let alone to represent other languages.
While a number of languages have been written using cuneiform, reading cuneiform is a very specialized skill: I took a class in Hittite language years ago, & the instructor simplified matters by omitting teaching cuneiform. (All of our texts were transliterated.) So unless your archeological party happened to have a professor in Semitic languages along, I figure all they could do is say, "Hey, this is written in cuneiform!"
The Phoenician alphabet makes a little more sense: the Phoenicians spread the use of their writing system thru the Mediterranean, & it was later modified to use with Etruscan & Greek. Even an archeologist with only a superficial knowledge of the topic could at least transliterate the inscription, & make a guess at the language it was written in. (IIRC, any competent archeologist working in European topics would know English & one or more of German, French, Italian & Spanish, as well as have some knowledge of Latin &/or ancient Greek. So they could guess from a transcription that it was written in either Proto-Celtic or Proto-Germanic.)
To say more, one would need to do more in-depth research.