I found the word 羨ましい but didn't found that kanji in Ringotan.
Are there some kanji left out on purpose or slipped this kanji just through?
If a kanji is not in your textbook, it will not be visible in Ringotan until you switch to another textbook/lesson plan.
The JLPT lesson contains 99% of the kanji in Ringotan (there are a few extremely rare ones in "Remember the Kanji" and "Kanji Kantai Test" which I didn't include in JLPT). If you switch your lesson to that, you can find 羨 in the custom review search.
