Also, one way that could easily jump start the village is to get their metallurgy technology up. It seems that most of the metal production is bronze with some iron (at least the swords didn't seem to be bronze) work. If you get materials and references on how to build a bloomery and import a couple of kilograms of pure bronze and iron from Japan, not only do they gain the knowhow of working with metals and advancing that, but they can also make their own devices and parts in-world from in-world materials (albeit much more easily and of much higher quality and knowing what they're doing). But, still, as long as the image of being just skilled craftsmen and not some super civilization is maintained, that's all that matters for now.
Of course, if he can get the Lord to remain true to his word, he could theoretically go all out and skip straight to the industrial age. But... That also brings attention from outside the village, as well. With their current build-up and population, it's much better to remain low visibility as possible.