Well, it's mostly about the work on the whole frame (and now that I've figured out that the contrast and saturation is way off on most of the FE cards it's about that too). The FE text boxes are smaller than those of post-mirage cards, which means more lines of text, which means problems with wording. Then there is a fact that the card type line is pre-
Urza's Destiny, which is different than what you'd expect today (creature types have been updated since then, enchantment types too, and there is no more interrupts now). And of course the rarity isn't displayed on the card.
When you're drafting, or just browsing through cards you got from a booster, it's much, much more beneficial if all this relevant info is displayed on the card rather than split between several panes. I'm using full card arts in Forge so I can see all arts if there are several available for the same card (as there are in FE), so for many old cards I can't get all the info I need without paying attention to 2-3 panels, and this way I (or anyone) can see most of it on the card itself.
The rarities are in fact important, as you can clearly see which card is a rare and which are uncommons and which rarity is missing from a booster you've been passed without mousing over the cards, even if you don't know all the cards in a set. It'll be clear what I'm talking about when I get them all done and do a video - I'll be able to simply enlarge the drafting box without a need for side panels at all (besides the deck building one).
And, well, now that I've got experience with this I can probably fix all the heavily oversaturated cards in the Invasion block which have been about equally mangled during scanning as the FE cards were, but in the opposite direction. Not to mention that if a card art has saturation problems, the way I'm doing it I can fix the problems with the art without over-saturating or over contrasting the frame which is also a problem with a few set scans, so Forge kinda ends up with the best card display art in the neightbourhood

It's a bit of a detour, but well worth it, and once FE draft tweaking is fully done, I'll do it first thing for the next set I work on so I don't have to dissapoint people who're expecting more tangible updates on the project.

However, maybe I'm missing something XD