Glyphs will automatically create the Lcaron with the traditional caron mark. Wikipedia tells me that in Slovak that the Lcaron is more usually represented by L’ rather than the caron. I don’t speak Slovak, so any suggestions would be appreciated.
If you look at Glyph Info, it actually knows that the correct component should be caroncomb.alt. If it doesn’t exist, Glyphs uses the normal caroncomb instead.
As for how caroncomb.alt should look like, to my mind it is a half of caron, a straighter shape rather than modified curly quotes; the curly shape feels not only wrong for the said reason but also potentially confusing with a quotation mark. It is also Peter Biľak’s preference (I asked him directly).
Thanks for clearing that up Tosche. Also for the visual description and link.