please check my translation

I'm translating this side note in a magazine and I am having difficulty with the accuracy and grammar

「ここで紹介されている三つのルールどおりに片づけたら、部屋が驚くほどすっきりしまし た！」
"If organizing by following the three big rules being introduced here, there will be a surprise at a room cleaned!"
といううれしいお便りをいただきました。
Pleasant information received.

it has a という so does that mean it is: a pleasant information called " " was received.
or is there a better way to say that? it sounds a little weird.
and I'm not sure if: "there will be a surprise at a room cleaned!" part
is the correct translation. the structure in Japanese was confusing to me.

kameimori said:

I
I'm translating this side note in a magazine and I am having difficulty with the accuracy and grammar

「ここで紹介されている三つのルールどおりに片づけたら、部屋が驚くほどすっきりしまし た！」
"If organizing by following the three big rules being introduced here, there will be a surprise at a room cleaned!"
といううれしいお便りをいただきました。
Pleasant information received.

it has a という so does that mean it is: a pleasant information called " " was received.
or is there a better way to say that? it sounds a little weird.
and I'm not sure if: "there will be a surprise at a room cleaned!" part
is the correct translation. the structure in Japanese was confusing to me.

Click to expand...

This is not supposition but a statement about what already happened.
～たら here can be interpreted as "then".
"I tidied up (my room) following the three rules introduced here, and my room became surprisingly clean and tidy!"

kameimori said:

といううれしいお便りをいただきました。
Pleasant information received.

it has a という so does that mean it is: a pleasant information called " " was received.
or is there a better way to say that? it sounds a little weird.
and I'm not sure if: "there will be a surprise at a room cleaned!" part
is the correct translation. the structure in Japanese was confusing to me.

Click to expand...

と（いう） is used to quote something.
I'm pleased to received a letter saying "I tidied up..."
うれしいお便り＝（受け取って）うれしいと感じるお便 り

Oh It became much more clear! Thank you!

about this part: "...my room became surprisingly clean and tidy!"
I'm wondering how would you know to use 'become'
because in this example it doesn't use the '...になる' pattern I'm familiar with.

with this part うれしいお便り
is there a rule or pattern or similar examples where phrases become shorter like that? why is that? is it because it's a magazine?

Also since this is an expository magazine about how to clean and organize, I didn't think personal statements using "I" was appropriate. Is there a difference in Japanese writing when writing an formal vs informal piece?

writing formally would this translation be still accurate?:
「ここで紹介されている三つのルールどおりに片づけたら、部屋が驚くほどすっきりしまし た！」といううれしいお便りをいただきました。
Pleasant letters received have said "When tidying up by following the three rules introduced here, the room became surprisingly clean and tidy!"

すっきりしました expresses the perfect tense rater than the past tense. It's more close to きれいになった than きれいだった. That's why undrentide-san used "became".

I would use "We received a pleasant letter" for うれしいお便りをいただきました.

Thank you for responding!
I was busy editing my post like crazy.
perfect tense is pretty new to me. I'll look more into it.
"We received a pleasant letter" seems more convenient to translate into a more formal writing style.