I've turned to playing with the emacs calendar and diary, and have
several suggestions for its surprisingly good Hebrew support. Attached
is an working elisp proof-of-concept.
Attach: /home/optimum/Projects/emacs-related/calendar-ivrit/cal-ivrit.el cal-ivrit.el

1) sunset-awareness. Currently, emacs does warn the user that a Hebrew
   date being presented is for the period midnight-sunset, but its
   trivial for emacs to check whether the current time is after sunset
   and to increment the date accordingly. In such cases, the date is
   labeled `eve of foo' to make it clear that sunset has been taken into
   account.

2) Hebrew data in Hebrew. Instead of transliterating Hebrew words into
   Latin characters, print them in unicode Hebrew.

2.1) This exposed three bugs in the bidi rendering of the diary buffer:

    A) Hebrew text lines in the diary are rendered left justified.

    B) Hebrew text lines in the diary are rendered in reverse sequence.

    C) RTL and LTR lines are rendered out of sequence to each other.

2.1.1) Bug A can be avoided by locally redefining the regexes that
       identify bidi paragraphs, and I've included that in the attached
       code.

2.1.2) Bugs B and C may possibly be related to bug #15541.

3) The code includes a generalized function for rendering Hebrew numbers
   for Hebrew dates, which is an improvement on a function
   `Footnote-hebrew-numeric' submitted in bug report #29759. There
   should only be a single function, generically named.

4) Parasha information is presented for the entire week leading up to
   its Shabbat reading. Currently, it's only displayed on Saturdays.

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