In general, the system probably shouldn't go in the title.
The system should be tagged. SE appends high-use tags to question titles in several situations (notably Google results). This means that if you both tag the system AND include it in the title, you'll get something like "WFRP -- WFRPT2e--Does Tzenntch..." Yuck.
This also leads to cleaner, more enticing question titles. Which helps draw people in who may know enough to answer your question, but don't meet the exact system (i.e. lore nuts, or people who can answer questions that aren't strictly RAW).
For many RPG systems, I would say that it's also a good idea to mention system/edition information in the body of the question. System is a nice detail to have somewhere that's a bit more durable than tags. For RPGs that don't have a large question volume yet and are at risk of tag-reaping, including the system in the body is essential.
This isn't a hard-and-fast rule, though. There are cases where disambiguating the system in the question title can be useful (particularly if a term in your question has meanings in several popular systems).