Katakana Expressions

In Hiragana, there are only 3 slurs, や,ゆ and よ.

But in Katakana, there can be other combinations, which is very confusing. For example, in the photo, expressions in the yellow boxes include katakana slurs other than ヤ,ユ and ヨ (red boxes indicate examples with ヤ,ユ and ヨ). Such as フェル in クアトロフェルマージ and ティin ツナ菓のごもり風味スパゲティー.

Other than that, there are new sounds in Katakana that did not exist in Hiragana. Such as "v" consonant sounds (va, vi, vu, ve and vo: ヴァ, ヴィ, ヴ, ヴェ and ヴォ) ; "ts" consonant sounds plus yōons (tsa, tsi, tse, tso: ツァ, ツィ, ツェ and ツォ) etc. I believe Japanese have created these words to accommodate more foreign words. We can see that these sounds do not exist in native Japanese as they are no where to be seen in Hiragana. When I visited Japan in summer, I was baffled when I tried to read menus in restaurants. Now I know it is because there are all sorts of special sounds in Katakana which makes the structure of words so complicated.

It took me a very long time to figure out how to type Katakata since so many of the sounds need to be typed specially. For example, the Katakana of "party": "パーティー, is typed by "paーtexi". The sound of "t-y" sounds nothing like "xi", and it is very weird. I had no idea how to type it before looking it up on the web.