You have to spend all or none commitment with Korean, Japanese and Arabic
You can skip around with German and Soanish because you know the English Alphabet
I would suggest that Korean is easier than Japanese and Arabic
Do not even study Japanese or Arabic until you learn the Korean Alphabet
Just take a notebook and write each consonant paired with each of the simple vowels
Do not even use Duolingo to learn it other than to remember the sounds
After you can write all the consonants from memory paired with simple vowels without looking at something else
Then you have memorized the alphabet for the first time & you can switch languages
Korean has an alphabetical order for the consonants learn it and write them in that order in the notebook until you can write in alphabeticak order without a guide
Next you can do that with Arabic or Japanese Alphabets but not the Japanese Pictograms
And switch between all three until you do not forget when you switch back to the previousv language
Arabic writing practice has to be done in a special way because the letter changes shape based on whers it is in a word
I have some typos where I hit one ketter off I assume you can figure it out
So to summarize it learning Korean and Arabic Alphabets require writing in a notebook the letters combined with other letters in addition to duolingo and putting in a lot of time up front until the alphabet is learned compared to English letter languages
@Stahesh
I mean require if you want to learn faster and to be able to write without a computer