Pension funds have taxation privileges that apply to the US and now to Japan, for VIAC (Finpension had Japan already included). I would try to maximize that and, considering all my assets (taxable, 3a, 2nd pillar) as a single portfolio, would use my 3a for the part invested in the US and/or Japan as much as I can.
All in all, I’d focus on a target global allocation for the whole portfolio, then use VIAC for the tax advantaged funds (CSIF US - PF, CSIF Japan - PF and/or CSIF World ex CH - PF Plus and/or CSIF World ex CH Small Cap - PF). Since I like simplicity, I’m using mainly the CSIF World ex CH - PF+ and CSIF World ex CH hedged - PF+ funds in VIAC.
Of course, the TER of the funds you would then use in your taxable account should also be taken into account.