They've since updated the access rules again. Seems they want to cover just about every cardholder and member possible.
According to the Chinese version of the website (which I've loosely translated) -
The Garden
Infinity MileageLands Diamond
Amex Black/EVA Air Cobrand Card
Citibank EVA Air Cobrand World Card
The Infinity
Infinity MilelageLands Diamond
EVA Royal Laurel/Premium Laurel/Business
Star Alliance First/Business
Amex Black/EVA Air Cobrand Card
Citibank EVA Air Cobrand World Card
The Star (which strangely has a blue sky theme)
Infinity MileageLands Diamond/Gold
EVA Royal Laurel/Premium Laurel/Business
Star Alliance First/Business
Star Alliance Gold
Amex Black/EVA Air Cobrand Card
Citibank EVA Air Cobrand World Card
Business customers and FFP members of codeshare partners and airlines which EVA does ground handling for
The Club
Infinity MileageLands Silver
"Industry Collaboration Partners and Birthday Cards"
Citibank Diamond Card
Diners Club
Citibank EVA Air Cobrand Titanium/Platinum Card
From the looks of things The Infinity and The Star would get pretty crowded during peak since The Garden doesn't have showers of its own. Otherwise if those that belong in The Garden stay there, the crowd should be dispersed across the four lounges.
Screenshot of lounge locations
