It's been discussed back when we were introduced to the multiverse. We ultimately had a decision back then. However, in recent seasons they decided to flop back and forth on how they designate earths. It's either the format of "Earth Two" (our current format) or "Earth-2".
As the latter is also more comic accurate, as well as them actually using the format on screen now, should we change earth designations to that format? Or should we keep things the way they are?
After a decision is made from the results of this discussion, the administrator and content moderator team will begin moving forward with adding 90's Flash content.