why can’t you be a beneficiary if you are not a resident?
when you say residency card, do you mean a local TW ID with an ID number?
like Marco wrote, there is a different between residents (people who live here more than 183 days a year) and citizens (ppl with TW passports that can live anywhere in the world).
To the best of my knowledge, if your marriage is registered in TW, there shouldn’t be a problem to name you as a beneficiary to insurance policies, a will, or to own real estate.
There could be some specific things i am not aware of, but to the best of my knowledge there is no legal barrier for this.
what problem did your wife encounter? who told her you can’t be part of the investment?