I think I have the original around and will add it here when found. I believe what I have below is (?) Mom's translation into English of this letter. Franz Apt was Dad's second cousin (the son of Grandfather's first cousin Waly Att), but was born in 1891, so closer in age to Grandfather. 

So l am meant to say the last words for the oldest of the family and the oldest friend, him who for many of us has long been the living bridge to a world that has long ceased to exist and has become a legend. Even though these were times when peace and security would seem to be assured, they were not, and it so easy for us to forget and know a way free of stress of all kind and sorrow and rue. And so also the way of Eugen Silbermann came out of the narrowness of a small family circle nourished by Jewish peace, so also was his way thorny in the beginning, full of obstacles and going zigzag. However, he did what in those days was not an everyday occurrence and made this young person early on familiar with other countries and their languages and their customs,[1] without however the magnetic needle the needle of this life was pointing to a certain goal. Then suddenly, one day came the breakthrough, the decision to become a dentist. This new beginning (from the beginning?) was for the no longer very young person in no way simple. But in the time where everybody with a full use of their strength was allowed to hope for reaching the goals set for by themselves, so this horizon also became less and less dark until it became broader and broader and when recognition was not absent and could not be absent and the recognition became the trust of a well rounded cricel (?) and eventually brought economic stability and a conscious relaxation in knowledge and achievement. But this consciousness in itself out of which came the thoughtful founding of a family is the sensible centerpoint of every endeavor. But this consciousness in itself could not and should not ever be made foggy the direct gaze or sense of modesty with which was his all his life his strength which he took out of the memory of the example of a much too early departed mother who was honored almost unlimitedly by friends and relatives. Eugen Silberman remained as we have all known him as the ever understanding and always helpful free of daily ambitions. He formed with time an equanimity, wisdom so that he fulfilled without knowing or even wanting to that sentence that an old father in a very famous place gives his son on his way.

"Your wisdom should be the wisdom of the grey hair, but your heart should be like the heart of an innocent childhood."

When finally the big storm came which also rattled the trunk of this big family so that many many leaves fell to the ground, so with God's help the three-parted circle was spared the most. But then what slowly developed in a new continent was [something] for which we were all witness. The success of the son and the last joyful thankful glance on the grandson this positive symbol of a future which is saying yes to life made more brilliant the last times of this slowly going to his end and emphatically cared for by his wife. If a man whose path on earth was successful and you take everything together happy, then to depart peacefully in his 80th year after death had been his companion that had been walking at his side for a long time, so for us standing by his coffin there is nothing left for us but to thank God. The memories of Eugen Silberman the man and his friend will live as long as we his life's companions for decades are still walking in the light.

Notes:

1. Again, an allusion to what grandfather did traveling. All I have is Dad telling me once about his father being in England at the time of Victoria's jubilee (which would have been her Diamond Jubilee in 1897). In his memories, Dad wrote: "Father would have liked me to go to England where he had spent some happy years as a young man. "