Re: Lanya (Taiwanese) etymology
First think to find out is of the name is Taiwanese Chinese or from a Taiwanese Aboriginal language. Identifying the language is the most important part of etymological work.
For Chinese names the standard procedure is to identify the Han characters used for writing the name and reporting their meanings. Note, that a simplified Romanisation ignoring tone usually merges several different Chinese names into one.
For Aboriginal names you need dictionaries of the source language to identify a meaning.
This is all I can help here.