In part this depends on personal preference and objective you have. If you want to be really organized then separate accounts is way to achieve that. But for me that is too much of a burden really. Gives a lot of real and mental/sensory overhead. For some things - with lack of federated identity - it is inevitable to have multiple account. Like I find myself talking to my other self between Lemmy and Mastodon :D
One thing to consider is if your followers like the combination of stuff you are interested in. If a large number of your posts are in Italian, then that may be a reason for English-speaking fedizens to not follow you anymore. Scholarly stuff and book stuff seem to go better together. NSFW not so much, for obvious reasons..