I mean this gently, but my first suggestion is to stop thinking of the dogs in terms of good/bad, fault or no fault, innocent or guilty.
There are so many complex micro aggressions between dogs that you will never really know if your dog is giving off a communication that other dogs are firing off (unless you video and slow-mo it).
For example, a fast speed tail wag, as I suspect you described, is not a universal indication of wanting to be friends. You have to look at the type of wag (stiff vs loose), the tail carriage (up vs down) and the dog's other body communication to determine that. It can also indicate a dog that is highly aroused, such as one readying for a fight - or 'bluffing' about being ready to put the other dog off starting something.
Best to come at the whole scenario with the view both dogs are struggling to get along with each other. It neutralises the sense of blame and defensiveness that can go with thinking 'my dog is friendly but yours is a PITA'.
All that said, it is NOT ok to allow any dog to follow another around when the other is attempting to gain distance. In an ideal scenario, your sister's dog would be allowed short interactions with your dog and then controlled so that it couldn't follow yours about (e.g. on lead). This gives them chance to grow to know each other without the relationship being soured by one being more keen than the other.
If your sister won't follow that then you will need to keep the vists with your dog to a minimal and perhaps ensure they contain an alterntive focus for the dogs than each other. e.g. a walk.
In terms of other dogs, yes some dogs do appear to 'attract aggression' but, as above, it's sometimes almost impossible to tell if the target dog did or moved in a way that is more likely to trigger this. Other factors include dogs being intact or unwell.
Mostly, it's best to give strange/unknown dogs good distance from each other until you are comfortable that they are both giving off very relaxed behaviour signals. Note: I said relaxed, not friendly. Friendly signals are easier to misinterpret. Even when correctly interpretted it can be easy for strange dogs to overstep a boundary and trigger a disagreement. Relaxed ones are normally much clearer and suggest the dogs are at ease with each other, thus less chance of it going wrong.