Another aspect to consider would be the “tax residence” of the foreign company.
Luckily, Taiwan does not seem to have CFC-rules in place which would make the foreign company a tax resident on Taiwan. However (see Corporate - Significant developments (PWC Taiwan) ):
The Income Tax Act was amended in July 2016 to include anti-tax avoidance rules in Article 43-3 (Controlled Foreign Company [CFC]) and Article 43-4 (Place of Effective Management [PEM]) of the Income Tax Act.
[…]
For PEM rules, under this new tax regime, if a foreign company meets all three criteria triggering the PEM definition, including (i) decision making location, (ii) record keeping and maintenance location, and (iii) actual operating location are all in Taiwan, the foreign enterprise will be deemed as having its head office in Taiwan and will be subject to tax assessment in accordance with the Taiwan Income Tax Act and other tax regulations. The Regulations Governing Places of Effective Management were announced by the Ministry of Finance in May 2017.
So in order to actually control a foreign company from Taiwan, at least “record keeping and maintenance location” have to be outside Taiwan in order for it not to become liable to pay taxes in Taiwan.
However, there is also this aspect ( Corporate - Taxes on corporate income ):
A non-resident company is taxed on income derived from Taiwan sources. A non-resident company with a fixed place of business (FPOB) or business agent in Taiwan is taxed similarly to a resident company (i.e. subject to filing of an annual CIT return based on the same CIT rate provided above). A non-resident company having no FPOB or business agent in Taiwan is subject to WHT at source on its Taiwan-sourced income
I think this means that having the owner of a foreign company permanently residing in Taiwan means that the foreign company has to file company income tax in Taiwan!
For me this means that I should either work self-employed or actually start a Taiwanese LLC.