C. erythraea have corymb-like cyme, sessile flowers, basal rosette, 4.5mm long petals.
The other key leading to C. pulchellum or C. tenuiflorum says dichasial cyme, with pedicellate flowers. Lacks or have a weak basal rosette.
I think the inflor shown in the photo is a dichasial cyme not corymb,
Cant say if flowers have pedicels, and the leaves are a bit high (cauline) rather than basal rosette.
If really not C. erythraea, the choice is between C pulchellum vs C. tenuiflorum, and depends between the position of the branching formation (low vs upper) and no. of internodes (3-4 vs 5-9)
The branching is almost along entire main stem (but more dense below) while if 'internodes' are branchings from main stem, then there are about 4-5!!
What do you think about this plant? C. pulchellum, C. tenuiflorum, C erythraea ?
So I also suppose that the photo just shows C. erythraea, maybe a bit atypical