For the most part I cant think of anything that needs stat adjustments, if we assume battlevalue gets updates. I also dont think a battlevalue change ruins the existing record sheets... while, like the older books with published BV values for 'bv1' and 'combat value', if they post BV3 as a tech manual errata (i have strong thoughts on what the fixes should be), the only change is the BV number on the record sheet calling to BV2, and new record sheets can have BV3 printed on it. For anyone actually using BV3, they will have the tool/resources to see the 'new' number, which they can pencil in on their old record sheets if they really want to.
As for tech, I agree things like rocket launchers which were back dated, along with about a dozen other things, kinda stings. There are numerous mechs in the 3rd succession war that would have greatly benefited from some of the retro tech, so its annoying to see it get post dated but never used. Pirate and periphery rocket mechs not being around in 3025 in cannon sources feels like a wasted opportunity, justified in universe by primitive rockets being too expensive, and justified out of universe cause in the 80s the rocket launcher didnt exist so didnt get talked about. Same with primitive mechs... there is great opportunity for 'cheap' low tech primitives to bulk up the failing tech base in the succession war, but it wasnt until the Jihad they had the idea to make less advanced version of mechs? Like, its a great idea immediately hamstrung by a lack of playability. So I agree with you mechanis.
As for the probe, at least in the older books hidden units was much more prevalent as a rule. It still shows up in the newer books, but with the focus on more 'versus' type stuff even in the chaos campain missions hidden units ambush killing your opponents stuff isnt popular for a versus game, unlike narrative/asymmetric games in older scenario books which weren't well balanced at all. A lot of missions now are giving the probe a different job, to avoid using hidden units rules in the interest of more fair gameplay. But seeing as the probe was build to counter hidden units, I think the very low BV of the probe combined with it still having situational usefulness means the probe is in a good spot, as far as BV is concerned.