No, not randomized. When my father studied French in school many, many decades ago, his textbook taught sentences such as "La plume de ma tante es sur la table de mon oncle" -- "My aunt's pen is on my uncle's table". Certainly nothing anyone would say normally, but a good educational tool nonetheless.
It's a regular -er verb:
This is a strange sentence or choice of words to use for "améliore".
I have never heard this expression in English, at least not the United States. One might say: "he improves the meal" or "he improves his recipe". Perhaps this could be changed to "Il améliore son discours."
rehausser = to enhance s'occuper = to fix ajouter = to add
Come on people use your dictionaries 'améliorer = to improve'! If you don't know a good one here are a few good ones.
English is a language composed of lots of other languages, and many of the words have multiple connotations. In English, we use "to fix" to mean "to make better," "to solve" (as in a problem), "to prepare" (as in food), and "to repair." However, French is more precise in its word choice. In certain contexts, I can see your translation as correct. Unfortunately, Duo isn't as sophisticated a program as the human brain, so it follows more precise rules. It can be frustrating, but try to remember to be as precise as possible when making translations within the program and to pick a word that has fewer meanings. It helps me to think about it like I'm trying to be as clear as possible to someone who is not a native speaker.
This page has the full conjugation of
It naturally ends in "s" in the singular and the plural has the same form, so "repas" can be either singular or plural. But you can tell from context which it is because any article/adjective/possessive must agree with it.