Spanish l+r pronunciation...advice when together?

[El Forastero]

But in may neutral andean colombian accent, we pronounce that s as a /z/ sound

Off topic: Do you pronounce the s like [z] in other positions too, for example in the word mismo?

Yes, before every voiced consonant, indeed: Israel, Isla, mismo, asno, rasgar, asbesto, esdrújula.

You can listen to me pronouncing those words: https://t.ly/dWYX

In Venezuela and Argentina, it's pronounced aspired:
In Other caribbean accents, there's a total elision
In Spain (please correct me), it's pronounced [s]

[tractor]

In Spain (please correct me), it's pronounced [s]

Depends on the dialect. In the South, it’s often aspirated or elided.