カタカナはむずかしい
If you are an English native speaker and took a Japanese course in the US, you might have had a hard time to memorize Kanji. However, the recent research showed that correct kanji spelling (writing ) is rather easier than katakana spelling (writing ) for English native speakers.
It is because kanji writing requires you to memorize the shape and strokes and to associate it with phonemic sounds (yomigana) of Japanese words while katakana writing (production) requires to memorize the shape and to associate with it with phonemic sounds of English (or other European languages) words.
You might have misspelled Katakana if you relied on your sound recognition.
For example, you write
ホーリーウッド as Hollywood
ベヴァリーヒルズ as Beverly Hills
because you want to write as you hear.
One of very interesting examples of katakana spelling with English name is ヘップバーン（Hepburn) as Audrey Hepburn and ヘボン（Hepburn) as James Curtis Hepburn, who is famous for romanization system (ヘボン式）.
I found not only English native speakers but also Chinese native speakers have hard time to spell out their names with katakana. Because they cannot find the exactly same sound of Japanese katakana sounds as their own sounds in Chinese, there are so many variation to spell their names in English and consequently spelling into Japanese.
ジャさん and ジェさん might share the same last name.
チョウさん and ジョウさん might share the same last name.
Please do not give up learning Japanese even though you did not get a good score on a Katakana quiz at Japanese 101. It is not your fault but the limitation of the Japanese language that has fewer sound systems than other languages.
My 10 year-old daughter wrote an essay in Japanese as "私は昨日、ホリーウッドのパレイドゥを見ました。ストーンムトゥルーパールもいました。” I know it is misspelling but I think it is OK because we know what she was talking about :)
