FWIW, there is now a user manual for Valentina (…which means it will probably be 95% the same as Seamly) in both English and Russian, available for 20 EUR. More details and a free preview PDF here.
LOL, I saw… It seemed very well done, judging from the preview I saw of the contents.
Ce manuel a également été traduit intégralement en français.
For complete information, this manual has been translated in French too.