The Finnish names such as the Lion are the modern ones, which are almost exclusively translations of the international names. Some of the constellations’ names are ancient, but they are well distributed in the Western world.
So, the ancient Finnish names are different. I didn’t really research them, and the SSSS names I came up with are based on the assumption that some of the survivors knew the official names, and they have been developing based on current circumstances. In fact many of the ancient Finnish constellations would likely be different, most of the omes I chose are very prominent but many of the official ones are quite hard to see.
Some of the Finnish traditional names were mentioned in the Wikipedia articles so here they are:
Orion with all his finery includes a lot more than the basic shape:
https://fi.m.wikipedia.org/wiki/Orion_(t%C3%A4hdist%C3%B6)#/media/Tiedosto%3AOrionin_t%C3%A4hdist%C3%B6.pngAncient Finns have seen Väinämöinen’s Belt, Väinämöinen’s Scythe or Sword of Kaleva in these stars. The Wikipedia article doesn’t mention the Finns having seen Väinämöinen himself holding the scythe, so I don’t know if that was the case. The arrangement for the Väinämöisen Viikate (scythe) is illustrated here:
https://www.aamulehti.fi/hyvaelama/art-2000007288213.html However he Kalevanmiekka (Kaleva’ Sword) is the same as Orion’s sword, and Väinämöisen Vyö (belt) is Orion’s belt, so it comes to mind that the Finns have seen Väinämöinen where we now call the guy Orion. While the Belt is the brightest and most prominent, the hourglass shape I included is very clearly visible and easy to distinguish and it would make sense that they could have been considered an entity.
Leo, nowadays in Finland the Lion, is one of the earliest constellations defined. Again the Finnish Wikipedia about it mentions that it used to be called Hiiden Hirvi (moose of Hiisi) or Jalopeura (Noble or Great Deer). It does look like it has antlers to me! But I went for the Great Cat because Leo would be much much more likely to be known by the original survivors, and that evolving into Great Cat seems plausible considering importance of cats and definite lack of lions in Y100 Finland.
The most important constellation for ancient Finns was and is however Otava, the Big Dipper, part of Ursa Major (why does the sky bear have a long tail??). It’s mentioned in the Kalevala in the firt poem where Väinämöinen is born and rises up to learn about Otava and about the stars in general. I didn’t include it, because it would not change.