Some key points (credit to reddit user showmeufos):
They found 700 spherules using their magnetic sled, and thus far have analyzed 57 of the 700 spherules.
They conducted mass-spectrometry on 47 of the 57 analyzed spherules thus far. Of those 47, 5 spherules reveal "a distinct extra-solar abundance pattern."
Since IM1’s spherules melted off the surface of the object, the enhanced "Be" abundance might represent a flag of cosmic-ray spallation on IM1’s surface along a extended interstellar journey through the Milky-Way galaxy. This constitutes a fourth indicator of an interstellar origin to IM1, in addition to its high speed, its heavy element composition and its iron isotope ratios.
The enhanced abundances of heavy elements may explain the high material strength inferred for IM1 based on the high ram-pressure it was able to sustain before disintegrating. The high material strength inferred for IM1 can potentially be tested experimentally by assembling a material mix based on the “BeLaU" composition, with proper compensation for lost volatile elements.
The "extra-solar" spherules have abundances of the elements Be, La and U, (abbreviated "BeLaU") by up to 3 orders of magnitude more than materials found within the solar-system do.
"The 'BeLaU' abundance pattern is not found in control regions outside of IM1's path and does not match commonly manufactured alloys or natural meteorites in the solar system."
This evidence points towards an association of "BeLaU"-type spherules with IM1, supporting its interstellar origin independently of the high velocity and unusual material strength implied from the CNEOS data.
They suggest that the "BeLaU" abundance pattern could have originated from a highly differentiated magma ocean of a planet with an iron core outside the solar system or from more exotic sources.
Yes, I agree. I believe they have a good idea of where a larger piece of material is located, and they are planning another expedition to determine whether this object is artificially made or not.