If also in C the Rogo glyph type indicates winter solstice we could use Ca3-25 as a point of reference in order to search for other cardinal points. But first we have to ascertain that there is no other similar glyph in C which could serve better for winter solstice.

These 12 glyphs are possible candidates and I have redmarked the most obvious ones:

Ca1-8	Ca3-25	Ca10-29	Ca11-3	Ca11-13
		7 on side a and 5 on side b
Ca14-219	Ca14-222
Cb5-16	Cb5-18	Cb7-24	Cb7-26	Cb14-12

While Ca3-25 is single, these glyphs mostly come in pairs, for instance:

Cb5-16	Cb5-18		Cb7-24	Cb7-26

I interpret this evidence so that the single Ca3-25 should be at winter solstice. Pairs of glyphs close together usually refer to a late stage in a cycle.