I have had an account with them but, I closed it.
The account is in Aussie dollars but, Investec have a big buy /sell spread so, you will lose in conversion back.
Also, it is 30 day notice so you have no way of knowing the conversion rate when you wish to withdraw.
Nansus
But it isn't really foreign investment income, if deposited with Investec. They will deduct Dirt before apying you interest.
There could possibly be a Capital Gains tax liability. You start with x euro, turn it into AUD. If when the account matures you get 2x euro, you've made a gain.