The LaTeX exporter does not honor the setting of org-list-allow-alphabetical.
I think it never did. Such a list is just an ordered list for export, the bullet type is just visual sugar in the Org buffer.
To force a special bulllet type, you should use other means (literal LaTeX). For example:
---------------------------------------------------------------
* test
1. skfkshafkj
2. fkjshfksj
#+LaTeX: {\renewcommand{\theenumi}{\alph{enumi}}
1. kajsfkjhf
2. fjsfksjhf
#+LaTeX: }
1. sss
2. ljhsdfkjh
---------------------------------------------------------------
I hope this helps.
- Carsten
It exports ordered alphabetical list as standard enumerate environment with numbered items.
org-mode 8.0.3
I placed the setq before loading ox-latex. I read in the docstring that org-list-allow-alphabetical should be set before org.el is loaded. I installed org-plus-contrib from ELPA and thus do not manually load org.el.
I found a post on this ml [1] on a related issue where the OP states that doing the setq before loading the exporter solved his issue.