As far as I know, there is no authoritative answer to the question of whether two funds from different companies that track the same index are "substantially identical" as per the wash sale rule. Here's a page discussing the issue:
http://www.fairmark.com/capgain/wash/wsident.htmIMHO, if you buy that fund in your 401k, it's a little risky - I wouldn't do it. (Assuming that it tracks the same index).
But you probably have another foreign stock fund in your 401k that is actively managed. You could use that. In fact, this is my plan for tax harvesting when I have a drop that is big enough to make it worth it to me. You can really only do this when you have foreign and US in both taxable and tax advantaged and you're willing to shift the proportion of US/foreign between the two spaces.
Essentially, you'd sell the VTIAX in taxable and buy VTSAX in taxable. In the 401k, you'd sell VTSAX (or whatever US total market fund you have) and buy the foreign actively managed fund. It's not a wash sale because you're moving from an indexed fund to an actively managed fund. After 31 days, you'd sell the foreign actively manged fund in the 401k and buy the index fund (SWISX in your case). You wouldn't worry about cap gains because it was done in tax advantaged space.
If foreign stocks have a loss, you can just buy back the fund you wanted in taxable and go back to your old allocation in the 401k, no sweat. If the foreign stocks bounce back, you get to participate (minus the active management fees for one month, pretty small) and don't get stuck with that fund. You couldn't keep this up indefinitely because you might eventually wind up with all US or foreign in tax advantaged, but as long as you've got both and you're indifferent as to which one is in taxable, it's feasible.