If Italo-Celtic is associated with Suvorovo (which would be the only possible CA Steppe->Europe migration afaik), wouldn't that make it a lot more archaic than Tocharian (likely Afanasevo)? Idk, I still like the idea of Yamnaya's Western expansion being Italo-Celtic-Illyrian (proto-Illyrian maturing in Vucedol and proto-Italo-Celtic maturing in contact zone with East BBs) and its Eastern expansion being proto-Tocharian (though I've toyed with the idea of Afanasevo not descending from Yamnaya but rather both descending from a Central Asian culture), as well as Kura-Araxes being proto-Anatolian, the Corded Ware spectrum going from proto-Germanic to Balto-Slavic to Indo-Iranian (though this spectrum and its descendants would include other languages such as Daco-Thracian-Cimmerian and Lusitanian-Belgian etcetera...), proto-Hellenic and proto-Armenian being from Late Yamnaya/Catacomb migrations into the Balkans and across the Caucasus respectively, and proto-Albanian I have no opinion as who knows really (first guess is Srubna and related to languages from that culture like perhaps Daco-Thracian-Cimmerian as it doesn't actually seem that closely related to what we know of Illyrian from what I've read, but afaik it also isn't really closely related to any language).
Literally none of what I wrote is useful in this debate but it's just what "feels" right to me. Some things I'll never believe in though (well unless there's new evidence), such as L51 originating in Yamnaya/Corded Ware (though I'm open to an earlier Steppe migration to Europe), Bell-Beakers of the L21 and DF27 branches speaking (proto-)Celtic (their linguistic affinities are interesting, personally I think L21 (and Central European DF27 immediately after contact with Rheinish CWC) spoke proto-Belgian-Lusitanian and DF27 when invading Iberia perhaps for the most part just took the Vasconic language of those they assimilated into (rather than exterminating like with L21)), or there ever having been some proto-Italo-Celtic-Germanic "Northwestern" language (i.e. Germanic is to be associated with Balto-Slavic and more distantly Indo-Iranian).
By the way, I think this proto-Lusitanian-Belgian connection needs to be looked into more, they are clearly even from my amateur understanding more closely related to each other than any other IE language and that fits perfectly with the original IE languages of L21 and DF27 before the linguistic replacement by U152 Celtic elites in Urnfield (q-celtic) followed by La Tene (p-celtic). So, after all of that, basically I think L51 BBs picked up IE (well, they COULD have spoken IE before that and just adopted a different IE language) from contact zones with Steppe-descended cultures they came across and dominated via elite status. Imagining P312 existing at the Upper Rhine or perhaps the Upper Danube, a Volkerwanderung of sorts would be triggered by the arrival of CWC in Germany. Those that migrated eastwards (U152, East BBs) mingled with and dominated Hungarian Yamnaya as is more or less indisputably seen with Hungarian Bell Beakers, picking up Italo-Celtic. Those that migrated down the Rhine and later to Britain (L21) are known to have been in heavy contact with elements of Rheinish CWC and would pick up their language (proto-Lusitanian-Belgian) - some DF27 would do the same but instead would migrate to Iberia, where instead of slaughtering most of the natives like L21 they would have (still with some slaughter of course!) picked up the Vasconic language of the natives as elites just as in all the other cases mentioned of language transferral. In other cases with DF27 language transferral would be more like with L21 - so L21 migrating down the Rhine (+ to UK) would be Belgian and DF27 that didn't adopt Vasconic (and perhaps was more violent and "exterminaty"?) would be Lusitanian. U106 would have made an earlier migration (via which route I don't know though I have basic ideas, this entirely depends on whether L51 was an original Bell Beaker lineage, or if it has a French or Central-Eastern European Urheimat) to the Single Grave culture where it would have picked up proto-Germanic - thus as both share a Western CWC origin, a proto-Germanic-Lusitanian-Belgian language could have existed around Eastern Germany before one branch of CW moved into Southern Scandinavia and the other continued Westwards to the Rhine. And just for fun, why not put the hypothesised Aegean language family and Anatolian together as proto-Aegean-Anatolian, associated with K-A spread (see Maciamo and others about e.g. Minoan descending from Kura-Araxes, and KA is the best candidate by far for Anatolian right now). Then you could go back EVEN further and say the KA branch that migrated Westwards would be proto-Aegean-Anatolian and that which migrated Eastwards would have spoken proto-Gutian, so K-A would be proto-Aegean-Anatolian-Gutian. God I love speculating, but it just feels so right. It probably is just simpler to say Suvorovo is the origin of proto-Anatolian though, via Ikiztepe, as that satisfies the need for proto-Anatolian to be a very early split. The problem with Suvorovo isn’t so much that there isn’t a trace in ancient Anatolian auDNA as heavy dilution explains that away, but rather that there isn’t a trace in Y DNA. There are
loads more, less attested likely IE and possibly IE languages, but besides proto-Euphratean (which to my mind is almost guaranteed to be legitimate given
this), none of the rest are that relevant to the basic question of IE spread and origins.
Hopefully this rant while pointless, isn't meaningless and actually makes sense. As I said, it's mostly just what feels right, but I'm pretty certain that's how almost everyone decides what to believe anyway. As I’m not motivated by ideology, hopefully I’ve come to a broadly correct conclusion.