Quoting myself because, in looking more closely at the plan, I think what I wrote here is wrong and was just me visually misinterpreting things due to the perspective of the artwork. Sorry about that.
Basically, I now think the stage is completely in-the-round, perhaps with a smalled, more defined tiered area that faces northeast. Circled below looks to be the dithered footprint of the stage underneath open-air shelter. The arrows indicate where guests can circulate to the left and right of the stage when moving from the EPCOT gardens into the Communicore Plaza.
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