The desired user interface for the concordance bears some similarity to Javadoc API documentation - it could consist of 3 frames: 1st frame allows to select some letter ("A", "Ā", "B", "C", "Č", etc.), the 2nd frame lists all the words starting with that letter (e.g. "abats", "abata", "abažūrs", "abējāds", etc.), and, finally, the 3rd large frame lists all the contexts in all the provided documents, where the selected word appears. Each of these contexts is supplied with a link, which allows jumping to the place, where that context appears and selects it.
In case of a Web/database application you do not produce the files for indices and separate words, but rather populate them with database queries.