According to my calculations, that room is the correct width but should be 256 + 256 + 207 = 719 pixels high. It isn't simply because you can't make it scroll down far enough. I can't be 100% sure for Symphony, but my alignment calculations proved right for every GBA Castlevania game so far, and for Symphony's Library (Edsword's map theoritically has a few places that should be filled, like the bottom of the save room and the bottom of the middle shaft which should end on the same level as the rooms on both sides. In any case, I'll report more once I started mapping myself.
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"With the first link, the chain is forged. The first speech censored, the first thought forbidden, the first freedom denied, chains us all irrevocably." [...] The first time any man's freedom is trodden on, we're all damaged. - Captain Jean-Luc Picard
B*tch, meet reality. Reality, meet b*tch. - Me