Sudah lama kita tidak berjumpa. Kita sekeluarga disini baik baik saja. Bagaimana dengan keadaan anda selama kita tidak berjumpa. Kita sangat rindu sekali dengan anda, sekarang ini kita tidak banyak waktu, ngapan kita bisa berjumpa lagi. Bagaimana dengan anak perempuan anda? Kalau anda ada waktu, harap kirim surat kembali kepada kita disini.
We haven't seen each other for a long time. Everything is alright with my family here. Has everything been well with you during all this time we haven't seen each other? We really miss you. But now we don't have so much time. When will we meet again?
And how is your daughter?
Whenever you have some free time, please write back to us.
"Was everything OK in the time..." should be:
"Has everything been OK during all this time we haven't seen each other?"
or
"Has everything been OK since we last saw each other?"
"Has everything been OK during all this time" the OK is too informal for a letter that is signed with Mrs. Bondan so I advise to change it to "Has everything been well with you during all this time..."
"Als u tijd hebt, stuur dan een brief terug naar ons." should be translated as: "Whenever you have some free time, please write back to us." instead of "Could you write back, if you have time?" as it is not a question but a request.