"Sana yazıyorum" means "I write to you".

"Seni yazıyorum" means something like "I write you." But if you say this is wrong; I guess it can be translated as "I write about you" Have a nice day.

This is the ideal form but not the absolute. Sometimes we form sentences very differently.

My attempt:

Bir gün taşları toplamakla çok meşgulken bir elmas yitirdiğinin farkına varacaksın.

good translation.

Thanks for your good wishes.

It is exactly the opposite. Let me correct it for you.

-e kala and -i geçe points that its about " var" or "geçiyor".

Thats for us to understand its not about "at"

 Is the "I " word also an abbreviated form of an old English word?

What you dont want to understand is it is not the literal translation of the Turkish adverb that you see in the books but this doesn´t mean the books are wrong. There is a saying: "Translation is like a woman; beautiful one is not loyal; loyal one is not beautiful." As you can see when we translate it literally it doesnt sound beautiful in English. If we want it to be beautiful we must bear its disloyalty to itself.

Yes I hate grammer. But I know what -e/ kala means. It can be translated as "in the period of  x time remains to y time" İnstead of translating this way they translate it as "at...to"