The Jawi script is a modified version of the Arabic alphabet brought to the Malay Peninsula and was spread throughout the Malay Archipelago when Arab missionaries and traders introduced Islam to the area in the 1300's to the 1400's. At first the Arabic script was mainly used for religious purposes, but it soon found quick acceptance with the newly converted population, assimilating with Classical Malay through the invention of certain characters not present in original Arabic such as ڤ , چ , ڠ , ݢ , ۏ and ڽ (V, G, NG, CH, P, and NY respectively). This was made to make the script more phonetic with spoken Malay. The script was further distanced from Arabic by the removal of the dash system so synonymous with the middle-eastern writing style sometime after it's introduction.
All in all, discounting the colonial era almost very written thing in the Malay peninsula, from the 1200's to the 1900's, were written in either the Jawi script a variant or it.
Nowadays, the script is only used for ceremonial and cultural reasons around the country, replaced by the Rumi Alphabet that most Malays are taught with. However, although the script has mostly disappeared in the cities, it is still used in the more rural areas of the country and the Pattani Thai Muslims still consider it as the main choice of day-to-day communication.
English/Japanese to Jawi translations
Boy, will there ever be changes! There shall be a lot of invented words due to the language barrier and syntax and grammar (Example: we don't have anything for "Ren" so "Byakuren" would be translated to "Byaku-r(i)n). If I were to list them all it would probably bloat the entire page! or at least length this little section to the point of over-importance.
So, I'm just going to say for now that there's going to be a lot of invented words and phonetic translations than usual using this script.
Also, since Gensokyo is a mostly rural area, I shall translate the overall sentence structure to be a bit broken and blunt to complement the setting.
...except if the characters have a voice or phonetic characterization, in which case the sentence structure would change according to who they are.
For the sake of keeping true to the title, here's a few basic translations:
Gensokyo = ݢنسوقيو
Hakurei Shrine = کوٴيل/توکوڠ﴾ حاکوري)
Toho Project = توهو ڤروجيک
Reimu Hakurei = ريمو حاکوري
Marisa Kirisame = ماريسا کيريسامي
Why the hassle? Is there anyone else who will care?
Probably not; I'm probably the only person in the entire world who will care about this! But... it'll be interesting to see if I can do it, and to see how much have I forgotten about the script and how much I can still learn from it. It'll certainly would make some use of my short free time.
And besides, a Touhou game with Arabic characters and yet would look totally illegible -not to mention not-understandable- to Arabic speakers!? This I've got to see!