Can I make '到達、落下 tōtatsu, rakka' one word? Like 到達落下 tōtatsurakka?

1. No, we don’t speak or write in this way. If you are foreigners – Oh, you are, we can guess the meaning of 到達落下, its meaning might be like -- XXX falls and reaches XXX place.
2. “Fall:落下” is an action and “reach:到達” is also an action. We can’t put 到達 and 落下 together to make sense.
3. The possible way is to put 落下 before 到達, but you still need to have a comma in between. Ex – The rocks 落下, 到達 the ….
In this way, you’re still describing two thing, so, in speaking, you need to pause a second after you say 落下, and then you say 到達.
I think the principle used here is the same as English; you can’t say “reaching and falling”, but I think you could say XXX “fall down from … and reach …” -- I think you’ve already known I’m not native English speaker, I’m an English learner here in Taiwan.
4. I don’t know how you pronounce this four Chinese character; the Pinyin of this four Chinese characters I check is dào dá luò xià.