Kind of a sad ending honestly, Takumi is clearly troubled by the missing memories of his wife and now that she's reincarnated she's basically a child... he has my sympathies honestly, he may enjoy his life now but it's clear he dearly misses his old life and his wife.
I'd be more happy if the ending was a timeskip or something to in the future, Nyacchi somehow regaining her memories and the two of them settling down in this new world as proper husband and wife. The ending we got instead is kind of like a shrug, like 'oh well she's a child and you're shit out of luck Takumi' and that's it, he's just stuck there cooking, revitalizing their food culture and it all cost him was a happy life with his beautiful wife. He really did get shafted, and for an isekai that's kind of a marvel in it's own ways, the dude got brought over to a different world because of a train crash and the most he got out of the deal was... his wife losing her memories and becoming a child...
That's crap luck.