I've managed this score, lower I think due to inefficent gem placement next to this east wall. So I'd think the 5088 is indeed the maximum, maybe can be pushed up to 5090 but not much higher. The main source that can be optimized is this upper-left puzzlebox
I have managed to extract everything from it save for these three grass tiles. Nothing is theoretically stopping it from having a better solution. I have then merged the 1-gem in the corner with a leftover from somewhere else