This is pretty black and white, at least from the Taiwanese side. The Taiwanese tax authorities have been very clear about the conditions under which resident and non-resident foreigners need to pay tax on income derived from Taiwan and abroad while physically present in Taiwan. 90 days or less - foreign income not taxed, 91-182 days - taxed as non-resident (bad), 183 days or more - taxed as resident. It’s stated in the Income Tax Act and pretty much every single guide about Taiwanese taxes you can find on the internet (and there are many).
I really don’t think you need an accountant or tax adviser here, at least for the time being. IIRC, you’ve been posting about this for a long time now (like your thread a couple of weeks ago asking about taxes for gold card holders, much of which applies here and that you already confirmed with the tax office). The questions you’re asking about tax liability in Taiwan and working on a visitor visa are honestly pretty basic and an accountant/tax adviser will tell you the same as you’re reading here for free. I’m sure they’ll happily take money from you for doing so, though.
I’d suggest first reading the Income Tax Act (it’s available in English) and the PWC tax guide for Taiwan (I think KPMG publishes one too, and maybe another consultancy firm, but you’ll have to google for those) to answer these basic questions (and probably some more advanced ones, like overseas assets). The rental income complicates things, but this stuff honestly isn’t that complicated if those are your only two sources of income.