I use
iroiro to convert ust aliases. Specifically
iroiro2 because while iroiro 1 has an english patch, it dosen't have romaji><hiragana or x-sampa converters.
You can download and place iroiro in your plugins like usual.
The option when you open the plugin (which is called 「僕の考えた最強のry Ver2.0」 in your menu) is ローマ字>ひらがな. This will open an easy to figure out grid of the original text and what it's replacing (which you can edit) then press 実行 on both windows to apply.