This is a typical abuse of auxiliary words in Chinese since great impact of Western languages from last century. Originally, Chinese did have 的 as marker for adjectives and 和 as a coordinator. But they're not used so often. In this sentence, it's unnecessary. Adding them makes it very awkward. This type of sentences are avoided in formal writing.
That been said, 和 is grammatical here. It's unnatural partly because this usage is rather new. Today it's not commonly used in the spoken languages and not fully internalized in the written language. Before the western impact from last century, 和 is normally only used to connect noun phrases in subject or object position.
的 is somewhat grammatically questionable, or at least orthographically debated. Normally, 状语 is used before a predicating verb or adjective, and 地 is a marker for 状语. By that standard, some scholars think that we should use 地 in cases like this. However, some scholars think that this rule shouldn't be applied to 程度副词, where people use 的 by habit. There are some regions in China where the local dialect distinguishes 的 and 地. For example, in my dialect, I tend to say it as 非常地(dì)迷人 instead of 的 (dí), though 非常 is a literary word for us and thus not usually used colloquially. I learned that there are other regions where people have different intuition than mine and think that it's 非常的迷人. This debate hasn't yet been settled, but 非常迷人 is considered correct by people from all regions. I have once discussed this question with my editor friend, and she said she always delete 的 or 地 in this case, whichever is used. (Words like 真的 are a different story since they're highly lexicalized.)
After deleting 和 and 的, it's completely grammatical, but we can take another step to make it even better by working on its prosody. 峨眉山的景色非常迷人秀丽 still reads a bit awkward. We have two adjectives here, 迷人 and 秀丽. The first one ends in level tones (平声) and the second in oblique tones (仄声). When they're juxtaposed like this, ending sentence with 平声 sounds much better. Thus
峨眉山的景色非常秀丽迷人。
峨眉山的景色 is the subject-topic, 非常秀丽迷人 is the predicate-comment. 非常 adverbially modifies the complex adjective-predicate 秀丽迷人.
We can also use 而 here. 和 is awkward but 而 is not (this sense is inherited from Classical/Literary Chinese). The tricky thing is that 而 can be used in many other relationships than simply juxtaposing (并列). On the one hand, it could be 递进. Thus the second adjective is better to have a stronger degree. Luckily in this case, thinking 迷人 is stronger than 秀丽 is reasonable. On the other hand, it could be cause and result. Again, luckily in this case, 秀丽 being the cause and 迷人 being the result is logical. Though due to the existence of 非常, the former relationship fits better. There could be other suitable relationships but I think I've made my point here. Thus
峨眉山的景色非常秀丽而迷人。
is a good sentence. One last point to note about this is that 而 is formal or literary, not commonly used in the colloquial languages.
The grammatical analysis of 钢琴非常的大和重 is the same. Again, the problem lies in prosody. Standardized Mandarin has a tendency to use disyllabic words. 大 and 重 cannot be simply juxtaposed since it's monosyllabic. Let aside the question of 的 and 地, both 钢琴非常的大和重 and 钢琴非常大和重 sound very awkward, breaking the regular pattern of prosody. 又……又…… is a very suitable choice here. But if you want to force in a 程度副词, making disyllabic Adjective Phrases and juxtaposing them could be a solution. For example,
钢琴很大很重。
Or we can add a punctuation:
钢琴很大、很重。
