So in this sentence "最も効果の高い頭痛薬はどれですか" Which according to Kanshudo, translates to "What's your strongest type of headache pill?", 最も seems to fill the role of 高い and it seems redundant?
Can anyone explain to me why it would be used this way, and why Japanese seems to use a lot of words in some sentences that can translate to one word in English? I'm JLPT N4 and still trying to come to an understanding of how "good" translation works.
There are a couple of things going on here.
First, you could certainly say the following.
効果の高い頭痛薬はどれですか
That would translate to
Which of your headache medicines are highly effective?
If you were instead to drop 高い, then you're left with an ungrammatical sentence
最も効果..??..頭痛薬はどれですか
First, how are you going to connect 効果 with 頭痛薬? You need some kind of glue here. Without 高い you'd need to have some other kind of connector.
But also, 最も is not describing 効果; it's an adverb. 最も is modifying 高い.
From this perspective,
最も効果の高い頭痛薬はどれですか
can be rendered
Which of your headache medicines are the most highly effective?
Consider Kanshudo's translation, which you provided,
What's your strongest type of headache pill?
Notice that strongest is a superlative. This is a grammatical feature of English that does not exist in Japanese. I'm not saying these ideas can't be expressed. Obviously they can, but there is no form an adjective can take to express this idea in Japanese. And even in English we have adjectives which also lack a superlative for: For example, consider the adjective excellent. You can't say "excellentest". To get the idea of a superlative you need a paraphrastic expression like "most excellent".
That's basically what's happening in the Japanese. たかい just means high. But, もっともたかい expresses the idea of higher or highest (translation depending on usage).
