Glagolitic Ⰾ (l) is like Ⰴ (d). Is it related to Latin / Old Latin l / d lingua dingua, lacrima dacrima?
The similarity of the Glagolitic glyphs is directly inherited from the similarity of the Greek letters Delta (Δ) and Lambda (Λ). Also for the Greek letter shapes there is no apparent linguistic motivation, they are just arbitrary and inherited themselves from the Phenician alphabet.
For some details see Wikipedia