not necessarily. If you added an murena cloud account (that you might have created?), the device could do the filesync. But the nextcloud client has more users, thus sees more bugfixes and can be more stable… in theory. See How to add the account and filepaths it syncs.
Calendar shares can be a headache if you require both accounts be able to write to it (instead of just subscribing to each other - that works cross-provider). Seems you have that solved for now, but there’d be threads on it in the forum.