For verbs with irregular humble/honorific forms, are the regular forms still used? * There are verbs with _irregular_ humble forms, e.g. the humble form of is . For these verbs, are the "normal humble conjugations" still used, or considered grammatical? Would be acceptable? * Similarly, there are verbs with _irregular_ honorific forms, e.g. the honorific form of is . For these verbs, are the "normal honorific conjugations" still used, or considered grammatical? Would and be acceptable?

“Are they used?” and “Are they acceptable?” are different questions. The regular forms such as and are used, but they are less formal than the irregular forms such as and . Whether the less formal expressions are acceptable or not depends on how formally you want to speak.

By the way, you are confusing grammatical terms “respectful form,” “humble form,” “polite form,” and “honorific form.” is the polite form of the humble form of , where the humble form of is . is the polite form of the respectful form of , where the respectful form of is . Whether an expression is in polite form or not is orthogonal to whether it is in respectful or humble form. Honorifics are the broader concept which includes all of respectful form, humble form, and polite form. For details, see Wikipedia.