Pronunciation not searchable?

From the LIFT source data, we build a mobile dictionary applications. In the source data, we use the pronunciation field that is used and rendered in the output - see the highlighted part in the figure.

The problem is that the user cannot search for pronuciacion.

Is this a feature (omitting some parts of the entry from the search) or is it a bug?

Only one quick update: part-of-speech is also not searchable: