A good guide for deciding what subjects to use for the calendar put out by a Karaite group would be the scope note for the heading Religious calendar (SH85-112615). The text of this note reads:

Here are entered texts and comparative studies of calendars of ritual observances for particular days.
*    Works on the Christian liturgical calendar are entered under Church calendar.
*    Works on the ritual calendars of other religions are entered here with the subdivision for the name of the religion, e.g.
            Religious calendars--Greek religion.
*    Works on the Islamic [Jewish, etc.] calendar from the viewpoint of chronological reckoning are entered under
            Calendar, Islamic [Jewish, etc.]

In accord with this note, if the focus of the work is on the religious observance for particular days or if the work contains liturgical readings for these days, then the appropriate first heading would be Religious calendars--Karaites.
This heading is currently authorized by the multiple heading Religious calendars--Greek religion [Judaism, etc.]
(SH85-112617). It could be that a work with this heading would not list all the days of the year but only particular  festivals.

On the other hand, if the work is an actual calendar and the focus is on the days and when they occur, then the first           heading should be Calendar, Karaite. You would need to propose this as a new heading on the pattern of
Calendar,  Jewish (SH85-18839) or Calendar, Samaritan (SH85-18846) .

Whether any additional headings would be appropriate depends on the content of the work.
 *   If there is a focus on the religious practices, then you could add Karaites--Customs and practices (for such a focus,             this seems better than Karaites--Religious life).
 *   If there is sufficient treatment of the festivals, you should propose the new heading Fasts and feasts--Karaites on the         pattern  of Fasts and feasts--Judaism (SH85-47421) or Fasts and feasts--Samaritan religion (SH85-47424).

The use of "Karaite" headings should make superfluous using  "Jewish" or "Judaism" headings, such as
Religious calendars--Judaism  (please note that Religious calendars--Jewish is not the acceptable form in any case).
However, if there is sufficient treatment given to a comparison of the Jewish and Karaite calendars, the additional             heading Calendar, Jewish (SH85-18839) would be appropriate.

Peter Kearney