Please use our Tips and notes (where available) or a dictionary https://en.wiktionary.org/wiki/r%C3%A1d#Declension
I also have trouble with this. The link you provided is not useful for me, at least. Sometimes it is maji rady, sometimes radi with an -i. I don't know when I should use which. I tried to find something online but I couldn't. I am not sure which unit it should be explained at because this 'food' is where it is the most prevalent but there is no tip about it :(
I think it is confusing to say viable and non-viable. We have not had that term yet. I think maybe you are saying animate and inanimate, which we have seen.
I appreciate the list of declensions. So Děti we know is plural and that leaves us the choice that it is either inanimate/non-viable (rády) or feminine plural (rády). Since children are not inanimate objects, the answer must be Děti is feminine plural and requires rády for that reason.
Thank all of you for your efforts.
Here's your answer. It translates perfectly this way: Children have a fondness (like) for sugar(/sweets). Děti mají rády cukr.
She has a fondness for (likes) Frantisek. So always try a few different ways of saying it and usually you'll find these types of things. Ask that question and look for a way it makes sense that may not be obvious at first.
This is not English, but a less used way of saying it would be 'Children HAVE a liking for sugar.' Liking would be a gerund. verb as a noun.
If it were an adverb it would not change with gender. It is an adjective, although in an old form.