OpenType is an excellent engine for the requirements of Biblical Hebrew. It is missing only a few things needed to produce perfect Biblical Hebrew.
First, Biblical Hebrew characters, like many other languages, require the correct placement of many diacritic marks.
These include:
1) the dagesh mark, a center point in a Hebrew letter;
2) the nikkud vowel symbol, which either appears under a letter (usually), or as a point above and on the left side of a Hebrew letter (known as a "cholam haser" or a missing cholam), or as a centered on the left side of a Hebrew letter (only if the letter is a final nuhn [plus kamatz], or a final chof [plus either a kamatz, dagesh kamatz, shvah {and I think there's also a very rare occurance of a dagesh shva}, and a final mehm with a chirik on the extreme right side under the letter), or the furtive patach, placed on the extreme right side, under the ayin, dotted hei, and chet, when these letters appear at the end of a Hebrew word, to indicate that the patach should be pronounched before the consonant, unlike how it is usually pronounced;
3) the cantorial music note, known as trup, or taamei mikra, or taamim for short, placed either above or below the Hebrew letter, indicarting how to chant the syllables;
4) the mysterious meteg (a short thin horizontal line, placed on the left side of the other lower glyphs, or by itself.
So, in all, there could be 0 to 3 upper markings, above the Hebrew letter, or 0 to 3 bottom markings, below the Hebrew letter, and another one smacked in the middle, or 0 to 2 diacritic glyphs placed beside the Hebrew letter.
Without trying to sound arrogant, I think Biblical Hebrew typographic conditional placement is the most complicated in the world!



