The pattern gives (or takes) what it promises: looks simple but requires patiency all the way through:
- Kihnu troi CO (Picture tutorial in Estonian helped me)

• facing (dash stich to join the facing is genious)
• managing two longish circular needels + wast yarn + stich holder in one sock, at the same time - magig looping, yes, but no way to manage two socks at the same time
• intarsia on the instep

The butterfly woud have been easier with duplicate stiches but now I think I know how to anchor the cc yarn in intarsia (before turning back, knit with the mc yarn two stiches beyond the last cc stich and secure the cc yarn, either by wrapping it round the mc yarn or LBJ stich which will be decreased away on the next row; I think the wrap method worked better here).

The heel decoration with duplicate stiches is my modification to the original pattern.