to look about, order, sequence, complicated thought which is not easy to express
覶 centers on looking around or examining things in a careful, sequential way. The idea of complicated thought that is hard to express extends naturally from this careful, ordered observation.
覶 combines 見 (to see) with a left component that likely contributes sound and possibly the idea of order or sequence. The exact historical development of the left side is uncertain.
The right side 見 means 'see'. The left side looks like a person (儿) under a roof (冂) with something like a hand (又) or tool, suggesting someone inside looking out and ordering what they see. Picture a person in a watchtower carefully looking about and trying to make sense of a complicated scene.
For ラ, imagine a person looking about and singing 'la la la' as they try to order their complicated thoughts: la -> ラ.