I'm willing to believe the the keys thing could easily have been code for drugs, and Christina was just being careful about what she put in a text message. It could be that many of the calls during the walk from CM to HF were on EA's behalf.
As there was no response by the time they reached the garage, EA gets impatient, pulls out his own phone, asks CM for HF number and and sends a direct message asking him if he had any good rock. I can't explain the other 2 messages from EA's phone that could have come from Christina, but she might not have not liked EA sending a direct drug request in a text.
HF was always in danger of being arrested and having LE seize his phone. She wouldn't have wanted to do anything to jeopardize him or herself.
All the stuff about keys lost, found, photographed, lost again never made any sense anyway, and nor did it make sense that Christina was calling HF constantly, even though she got no response. If you add the drug angle, it makes a little more sense to me.
Just my opinion, and I could be totally wrong!