On crooked toes... sometimes it is genetic, inbreeding does this. HOWEVER, I have found that mean roos get crooked toes later. I have had some of my meanest roosters start showing aggression and then get crooked toes. I think they just flog and break them. There is nothing anyone can say to make me think different on that one. I have seen it far too many times... straight toes, puberty, attitude, crooked toes. In that order.
Also, if incubation temps are just a bit high, you'll get leg and toe issues.
So in my opinion, if you KNOW your temps were right, and so far this bird hasn't flogged or been charging you or anything else.... it's probrably a sign of inbreeding. If GF is importing more bloodlines into the US, they are still "GF" or "Bradshaw" lines to us in the US... but genetically should be more diverse.
That said, most often the most celebrated lines in any breed are the ones that are line bred for years... sometimes decades. If you are like me and have tried some of these lines, you know they are less than hardy, have leg and foot issues, hatching issues (due to the legs being deformed and weak), often short beaks, but darn do the survivors look good. (ha) Since the SFH has no set color pattern standard... or even a SOP in the US at all... the biggest pressure is to make sure the fittest birds go on to breed. If all your birds are equal in health except for one crooked toe... maybe a pet flock would be a good idea. A place for the less than stellar, but not exactly stew worthy birds to go.