When is it generally OK to use capital variable names? For example, is it fine to use

LocalInfo.current.bottomBarItems

as part of my CompositionLocal or should it be BottomBarItems?

Variable names should always be lowerCamelCase. Compose-specific convention is only to use UpperCamelCase for @Composable functions that produce UI. e.g.:

@Composable
fun MyButton {
  Button(...)
}

// BUT

@Composable
fun <T> rememberMutableStateOf(default: T): MutableState<T> = remember{mutableStateOf(default)}