Smell, not that I remember. Sound, all the time. I’ll have conversations or hear people saying things, sometimes in different languages. Sometimes a word comes to mind that seems totally real, but usually it’s not. Some of the more detailed dreams have had storms, sirens, earthquakes (that eerie rumbling they have). Or even music.
You can think of “le” as a way of showing that it’s a syllabic L. Meaning that you say a dark L, and there isn’t really a vowel before it. The L takes up the whole syllable. It can sound like there’s a schwa in there (usually just a blip of one), but that’s just part of how you say the dark L. It comes from having the back part of your tongue press down and back.
This happens at the end of a word when the L is in an unstressed syllable. The spelling can vary a little. For example:
There isn’t really a reason why the spelling is different. That’s just how it happened to develop.
The pronunciation can vary a little too. If you hold the L longer, or emphasize the syllable more, it can sound more like a proper vowel is in there. But your tongue stays a tiny bit lower than it does for the schwa sounds.