I agree, he's probably too obvious. It's at the point now where when he comes on stage he might as well be waving a giant "Look at me, I have motive!" flag over his head.
One issue, it's not clear that Jason's murder is a mystery that we, as the audience, are
meant to be able to solve. Some mystery novels you can. Others you can't. I read both and generally prefer the latter, usually because I'll solve the former well before the characters do.
Riverdale, to me, seems to have pushed the murder to the backburner -- it's not trotting out clues and suspects every episode anymore -- which leads me to think that, if Jason's murderer isn't blindingly obvious like Betty's dad, the series will pull out some unexpected (and unknown) character out of the hat. Or, like the Adena Watson case on
Homicide, there will never be resolution to the case.
It occurs to me there's a strong meta reason why Betty's dad isn't the murderer -- Betty is the archetypal girl-next-door, and to have her father premeditatedly murder her sister's boyfriend would do severe damage to the character and her archetype.