"I bought a PC yesterday."
keep calm and blame the french. In france, they thought it would be clever to call "macdonalds" "macdo" for short, and the whole world thinks that's a normal word now while everyone in america wouldn't know what macdo is. In fact if the japanese said "ミキジーズ" it would be an american short version "mickey-D's" which means McDonalds
Mc and Mac are different language roots
i understand that transliterations are hard, but it's a very serious problem if the person who officially makes it doesn't know how to pronounce the word. The person who wrote that in kana didn't understand english and thought it was pronounced "poh-lee-pro-pee-len" which is just flat out wrong.
If they had the internet, they would have said "ポリプロパリン” ...the fact is that japanese is probably the most basic structure of all language... writing complex foreign alphabets are hard. good luck transliterating arabic to kana those who are reading this comment in a few years when the arabic course is finally up to a usable par (it was just created early this year)
immortal mistransliterations are actually all around you, they're usually in names of immigrants. There are a great number of incorrect names that came from german, russian etc. in early American-European settling.
a horrid example is Jakovsky ...this is actually a back and forth problem. There is a common slovak letter "ya" which is я. Because of how in german "ja" makes that sound, and, Poland... someone a long long time ago decided that "j" is actually "y" for english transliteration, and so, instead of properly writing "yakovski / yakofski" (which name likely exists as name mistransliterations tend to have correct and incorrect versions once people figure it out) we say "jackoffski" which is very.. very wrong.
note: the sound "j" doesn't exist in russian. at all. for the name jack they have to write "d zh eh k" джэк
パソコン is the object in this sentence, not the subject, so を is appropriate here. The subject, possibly the speaker, is implied. I believe you can use は to contrast with something else. For example, "テレビを買いませんでした。でも、パソコンは買いました。" This does not necessarily change subject, so パソコン would still be the object in that sentence. I'm a little rusty on this topic so someone please correct me if I'm wrong.