When I mix Kanji, Hiragana, and Katakana, is it ok to not convert everything to Kanji that can be?

Working on lesson 5.2.  I can read and write Hiragana and Katakana (albeit slowly) and just starting Kanji.  When I mix Kanji with Hiragana and Katakana in a sentence, is it okay to not convert everything that can be represented by Kanji to Kanji?  Here's an example:

おんな　の　ひと　は　むずかしい　です　か？

女　is the Kanji for おんな, and I know this one
人　is the Kanji for ひと, and I know this one as well

If I enter 女の人は　むずかしい　です　か？　In "Write It Native" on my iPhone, the  software responds by changing the font on むずか　to red font indicating I did something wrong and then changes it to the Kanji 難　(which I don't know, yet) in black 'font' with rest of characters green.

If I enter either 

1) おんな の ひと は むずかしい です か？
or
2) 女の人は 難しい です か？

then all is well.

Not sure if this is because I messed up or the software just compares what I typed to either of options 1 or 2 and since I entered a hybrid of the two the software assumed I messed up.

From my perspective I'd rather start using Kanji in sentences as I learn them rather than wait until I learn all Kanji, even if I don't convert everything to Kanji that could be.  I think I can just click the "good" button and override the error but don't want to do that if I've really messed up. And not sure how this would impact my score on the Certification test or benchmark?

Appreciate your feedback.

クレイグ

In my experience the software does not care for "hybrid" answers (maybe it's different in later levels, I'm in Level 1). If I complete the reinforcement  exercises using the handful of kanji I know, it marks the kanji as incorrect. The grade (red/yellow/green) can be changed manually, but I just type the answers in hiragana since it's faster and gives an all green result.

The course is riddled with mistakes where correct kanji is not recognised. Your option 2 was correct. Sometimes you have to convert individual words to kanji before writing the next word otherwise you will end up with a tail of the sentence in hiragana when it should be in kanji.

That said there are many kanji words in the whole course that the Japanese simply do not use at all!