Help with English text?

“Herein” might replace “hereto”.

There are no flagrant errors in the text, but as @dougiedawg has alluded, the language is somewhat “stilted”. That is, apart from being “formal”, as proper business English should be, it is overly formal, formal almost to the point of parody.

This project’s sales report is attached. The report is organized by building [identification? address? name? what?] and by the dates of sale. This report covers sales from [when?] to 31 Dec 2012. [Since the report is the topic, and all sentences are on the same topic, they can be combined in a single three-sentence paragraph. I used “dates of sale”, as it appears there are multiple sales. I always suggest that international correspondence containing dates should be in the form dd Mmm yyyy, because where you read a date such as 6. 8. 12 as August 6, Americans read it as June 8. Avoid that. Surely anyone will understand 31.12.2012, but if you use that format now, then it will be hard to change when you need to say 6 Aug 2012 instead.]

Contracts executed in NIS are converted into US dollars [the word dollar is not a proper noun] by the dollar exchange rate [whose rate? this can be crucial, business-wise] on the day of execution. [“Execution” is a more businesslike term than simple “signing”. Since multiple parties may have to sign a contract for it to become effective, “execution” occurs when all parties have agreed and signed. Also, are the contracts actually “converted” to US$, or simply “valued” for purposes of normalization? Your sentence needs to say “what is actually done”. “Conversion” implies an exchange of funds or ownership documents into US accounts, which may not be your intent.]

Certified copies of sales reports for prior years have been sent to you previously for each year of ownership, and are also duplicated here for your convenience. [Avoid phrases such as “we would like” when they aren’t necessary. The verb tense “was sent” is not quite correct, if I understand your meaning, because you “have sent” those reports – it is an action that continues into the present – and it is redundant and somewhat insulting to state that “you have already received it – actually “them” – before.]

I would drop the “hereto.”

“A sales report of this project is attached” works rather well. The word “hereto” is really never used by a native English speaker.

Looks good to me, and I am pretty good. I rather like the “formality” of it – that is how I write business communication. You just need to tweak that last little bit. Don’t use “already” and “before” both, that is redundant. Either they already received it or they received it before – one or the other.