Complex sentence: Words like "fault" and "vault" did not undergo L-vocalization, but rather L-restoration, having previously been L-vocalized independently in Old French and lacking the in Middle English, but having it restored by Early Modern English.
Split into simpler sentences: Words like "fault" and "vault" did not undergo L-vocalization but rather L-restoration. They had previously been L-vocalized independently in Old French and lacked the in Middle English but had it restored by Early Modern English.