I was in the same situation with BOI. The first time I did it I explained to the Bank Clerk and they advised me not to worry and they did not note down the Intermediary details.
The money was lost for about 2 months and took many phone call to find.
(the money was in some Limbo where no one could locate, very worrying)
So since then I bring a printed of the email with all the details into the bank, get them to write down on the form the Intermediary bank details (even though a box is not provided), I get them to photocopy my printed email (on which I have highlighted the Intermediary bank details), and staple it to the form.
I ensure they do this every time and I have not lost money since. It work and it gives me peace of mind.
Jimmy