I am bit confused here, these aliases are half kana half romaji, so it will just swap these characters? And what if I rename these aliases into only latin characters and eventually also conversely?
As partial said, for VCV banks the format most be "- kana" or "romaji vowel + kana". That's because it's a VCV bank.
i.e. [- あ] [a あ]
You asked if you can just change the the aliases to latin letters and well, it's kind of tricky. It would cause issues since UTAU won't know which file you're trying to call on if you do it like a normal CV.
For example, for a vowels alone, there's about quite a bit of them.
1. Starting note. i.e. [- あ]
2. Vowel to Vowel transitions. e.g. [a あ] [a い] [a お] [a え] [a う] [a ん]... [i あ] [e あ] [o あ] [u あ] [n あ]
3. Vowel to CV transitions. e.g. [a か] [a ち] [a も] [a れ] [a ふ] [a な], etc...
Now, if you meant changing the entire oto to romaji, you can do that. Therefore, aliases will change from [- あ] would become [- a] and [a か] would become [a ka]. This is a alright solution (if this is what you want) but it's quite rare for people to release romaji VCV USTs so you'll have to manually convert them on your own, and it causes issues with some plugins since they're more made to work with kana than with romaji.