Banco de *** - worst customer service ever!

There is no way a cashier's cheque should take that long.
Inform your home bank of this crazy delay and tell the Barcelona bank you'll issue a fraud complaint to the police if they don't get it sorted out immediately.
Light a fire under their arses and see what happens.

We bank with ****and have never had any issues.  That said we didn't use a cashiers checked.  We established the account with a few hundred euros in Cash and then from that point on, wired our money over.   I am sorry you are having these issues.  Do file a complaint and speak with the upper management.  No way should it take that long, no more than a few days in total.  Someone really messed up.

I generally find Spanish banks to be over bureaucratic, slow, expensive and inefficient.

I use banco Santander and my wife BBVA and we havent had problems. If you are expats and staying for a while the  Santander 123 account is attractive as it pays interest. I wire my money in Euros from a US FX account, Worldfirst,  and have not had problems with them. They transfer to Banco Santander as soon as they receive a wire from my US credit union. A transfer normally takes 2 working days. I normally pay about 1% on money transfers as compared with bank transfer rates (see xrates online, for example), but that depends on the amount you send. I haven't ever used cashier's checks, but from past transactions I have found that anytime you change money you need to know how the exchange rate will be computed and commissions. Not knowing these in advance will cost you money. The only cheaper way to transfer are credit cards that use banks rates and do not charge a commission. I have a Citi plat and previously a Brit air chase visa card. These can work well, but the cards generally cost about $100 per year.

Erased my message.

I have opened a Spanish bank account and have transferred money through Transfer wise which has been hassle free and they only charged .5%. I was transferring from UK so US might be different.  Patrick

Firstly, change your bank.  Talk to others about the quality of service they receive from their banks.

My preference is a small bank who have the time to get to know you personally. My absolute favourite is Colonya, Caixa de Pollença.  Check to see if there's a branch near you.  They are an ethical bank with head offices in Mallorca.  My experience of their service is first class and they treat you as an individual.  I opened an account and the second time I called a few days later, they already remembered my name.  It is always helpful to have someone the other side of the counter that speaks better English than you speak Spanish.

I opened an Ope.....   account which is a sub-brand by S........ and had nothing but trouble with it. The idea is that one can use the bank offices of S......., but at those offices in my area the deposit machines break down almost daily. Then I am forced to go to the counter to deposit, but, unlike with other banks, they require then that I show an id AND know my bank account number by heart, because their computers do not really have account information from their sub-brand account holders.
On top of that the sub-brand its website doe snot give the right balance information, as it does not keep track of pending debits in the balance. For that one has to look up a separate obscure difficult to find section on the site which mentions only how much is pending, but the system allows to overdraw unnecessarily this way.
I'm going back to my old midsize local area bank AB, where I pay more in transfer fees, but at least they know me there personally and never ask for ids and their machines work for sure, plus there deposit machines are also outside so accessible outside office hours as opposed to the other bank.
Banking in general is tough here. The wise man instead keeps his bank account in another EU country and uses that account its IBAN number for payments here. If you get your pension from abroad that should be no issue as the money gets deposited abroad then and no local deposit is needed.
Transferring the money from the USA via Transferwise is usually very inexpensive and fast (2-5 days).
Still, I recommend, to avoid fees and bureaucracy, to open a European bank account elsewhere, not in Spain. There are various services now that allow that like DKB and N26 in Germany. One can do the ID thing online with them using video a sit is required in all European countrie snow.

I opened an account with Caja  Rural in Los Montesinos.  Staff could not have been more helpful.   It was hassle free.  Patrick