Registration abroad does not by itself remove an Israeli obligation. What matters is where the company actually operates and where it is managed and controlled. If activity, staff or decision-making sit in Israel, an Israeli filing obligation can arise regardless of where the entity was incorporated.
It depends entirely on where the company is managed and where it operates. Israeli residency of the owner is a relevant factor but not the only one.
Tax treaties allocate taxing rights and can prevent the same income being taxed twice, but they do not remove filing obligations by themselves.
Occasional sales and sustained structured activity are treated differently. The distinction is factual and worth checking rather than assuming.