Sorry to hear about your accident.
Based on your account of the events I think there is a good chance that the RSL didn't activate your reserve, and played no role in the reserve malfunction.
You could look at the reserve cable, they often get a kink in them when there is a RSL initiated reserve deployment.
But like you say in the quote before, you pulled the reserve handle, or at least that is what I interpret your comment "reserve deployment" to mean in that sequence.
This sounds like a pilot chute in tow, or potentially a pilot chute that is stuck in the low pressure burble above you or even sucked right on to your container. Pchapman's has a good potential account above for the PCIT scenario.
You did the right thing to initiate emergency procedures.
What happens next is a bit of luck. Once the reserve is deploying the main container may stay closed if there is a misrouted or pierced bridle, or it may open up and the main may start deploying because having the reserve tray open and the reserve out relieves some pressure and tension on the main container which allows the closing pin to finally clear the closing loop.
There may be things that you could have done differently, or it could have just been a spot of bad luck. You may never be able to determine exactly what happened here but you can talk with your instructors and experienced skydivers to help avoid it in the future.
Know your gear, ensure that is is properly maintained, properly configured, and operate it correctly.
Practice your emergency procedures. Review how you will respond to different circumstances.
Plan your jumps from take off all the way till you are back safely in the packing area.
Build awareness about what other skydivers are doing.
You may also want to talk about your accident with a therapist who specializes in traumatic accidents and events. Having an accident, especially one that has many questions, can leave you with a lot of mental stuff to process.