I agree with this last assessment - way, way too late in the game Germany realized it needed more effective bomber interceptors. It tried to develop these quickly, and the design inventiveness and variety they showed was/is incredible, but the inability to do the rest of the tasks involved in addressing the problem - e.g., produce enough of the most effective designs and put enough capable pilots in them - was also evident. In terms of approach, the Me 109 or Fw 190 certainly seems to have been their "best bets" in hindsight, perhaps also the 262 if it had been able to be produced sooner, and in much greater numbers. But the sheer number and variety of designs developed really is amazing.
Re: Interceptor twin engined prop designs' failings vs. single-engine ones, the issue was shared by the US as well but thanks to the P-38's better overall design (IMO), as well as the outcome of the war, it is heralded as a classic. Nevertheless many retroactively see the continued use of the Lightning in Europe as a comparative misallocation of resources vs. other US fighter designs which were much cheaper to produce and maintain, and as effective (or more so) in combat. That said, the P-38 had it's advantages and was the 8th AF's best-available fighter escort until the advent of the P-47 and later the Merlin-engined P-51s. After replacement for the escort role, the decision makers involved likely felt that sunk cost dictated a re-purposing of the plane pilots and crews for ground attack missions was the most prudent thing to do. In the Pacific things were different and the P-38's footing as a uniquely capable fighter for that theatre stayed obvious through to end of hostilities, though even there the P-51 began to displace it in '45.
As to the Me 410, I can only say that Lt. Royal D. Frey - were he alive today - would probably disagree with those who say it was no match for a P-38, as he was shot down by one in February 1944 over Germany. And even moreso, everyone involved in USAAF Mission 311 would likely have a similarly fearful view of the effectiveness of the Me 410.
That said, the performance numbers for each are what they are, and the Luftwaffe did what it did surely for good reasons. Probably IS safe to say Germany should've done more to prioritize production to the designs that had the best combination of economy and performance, but I see their decisions as perhaps inevitable, given their faith in design superiority vs. quantity in general (one could say this about their approach to tanks as well, for example). Ironically the U.S. military industrial complex also seems to be adopting this strategy today as opposed to the strategies of the Russians and Chinese.