When the dust finally settled at the end of Crisis on Infinite Earths, not all was necessarily said and done. A single universe had replaced the old multiverse, and all realities had fusioned into one. It was necessary to create a new continuity. Marv Wolfman and George Pérez took the first huge step with "History of the DC Universe", a two-issue mini-series that gave us the first glimpse at the unified continuity.
Mera made the cut in issue number 2, and although she got only a one-line reference, she did get what you would consider significant page space with the beautiful pinup you see below by the talented Mr. Pérez.
I dont's know whether it was a simple mistake, or the beginning of an attempt at relaunching the character's history, but Mera was not born in another galaxy. Technically speaking, Xebel is a world in another dimension (initially referred to as 'Dimension Aqua'), not in another galaxy. This is the only time I have seen Xebel not being referred to as an other dimensional world.