As a native Spanish speaker, the bank has a couple of major problems (I hope you don't take this the wrong way; I just want to help you make better voice banks!)
1: Lack of VCs. The Spanish language often uses VCs (e.g., to-or-ta), since, although only consonants can be used, VC is more fluid.
2. Lack of phonemes with the "l" and "r" in the middle: I think this is the most important mistake. These phonemes are absolutely necessary to synthesize Spanish, since in extremely basic words, we have these phonemes (e.g., "gracias"), these are the following consonants that DO require their combination with the R and L in the middle:
B (BRIllar, haBLAr)
D (DRAma, mataDLA) (actually, dla, dle, dli, dlo, and dlu are rarely used, but they are part of the language)
F (FRAgancia, FLAco)
G (GRIllo, GLUcosa)
K (when the C is joined with the R and the L, it becomes a K) (KLAudia, KREar)
T (aTRAer, aTLEta)
P (PRAdera, aPLAuso)
3. Lack of the "ll"; the double L is somewhat This is necessary in the language. This is difficult to describe, and there are two variants of it: the Rioplatence (mine, pronounced sha, and separated from the "ll" in the Spanish reclists) and the general "ll," which is the one I definitely recommend recording.
4. The Ñ is entered in the reclists as nJ, nn, or ny, since UTAU doesn't support it.
5. Rs (the normal R and the RR) are mispronounced, as they sound like American ones. Rs in Spanish are similar to Japanese ones.
If you want to record a bank in Spanish again, I recommend looking at the pronunciation and using the Japanese one as a guide, since there are very few changes between the two. You should also choose a method like Aku-P's VCCV, or nJokis, which has a pronunciation guide for native English speakers. If you need guidance on how to pronounce something, I can help you by recording the phonemes so you can use them as a guide!