I have actually been enjoying Jubilee quite a lot but even If I am having fun her kit feels very clunky at points, and I think parts of it contribute negatively to Rivals experience (visual clutter and too many lingering AoE effects).

\-Only being able to critically hit with The Hood team-up, and low ammo count does not feel great.  
\-Her movement feels incredibly lacking when she feels like she is intended to be a mobile hero.  
\-Her Right click be a lingering AoE orb contributes to the visual clutter problem and also the problem of their just being too many lingering AoE effects which I do think makes the Rivals experience worse.   
\-Her E being completely tied another ability imo is just bad design.

My suggestions to fix this would be  
\-Let her crit naturally but give it a lower crit value like Psylocke. Triple her ammo count. Remove the attack speed boost from the clearing Sparkle Marks.   
\-Give her innate double jump and slow fall. Have it so her shift gives her a small dash and then 40% movement speed buff, the cooldown for the ability starts when the speed boost buff ends. Maybe put her at 250 health as a compensation.  
\-Have her Right click just be a one time AoE explosion that you can charge. Reduce the cooldown to 8 seconds. The damage range should go from 60-100 and radius going from 4-8 meters with 1 second being a full charge. Have it so if you charging mid air it auto slow falls you.

An idea for E would be taking the AoE explosion from her Shift and turning it into its own ability. Possible ideas would be a 100 health barrier that explodes if it is either destroyed or after like 4 seconds. That might make her too annoying to kill though even if she only had 250 health.

Jubilee is fun, but I think she has glaring issues.