The following is my translation of the song "那裏是吾家":
足跡遍天下，看透異國繁華， (My footprints are all over the world, I've seen every flourishing foreign countries
桃源仙境似夢也，始終找不到吾家。 (utopia is but a dream, I've never found my home)
安居似虛話，遠處密罩雲霞， (live in peace is like a lie, faraway places are thickly covered by clouds and mist)
何時一朝見霧化，子孫歡笑艷陽下。 (When will be a day when we see the mist dissipate, and my children laughing under the bright sun)
啊！萬千燈火透廣廈， 啊！那裏是吾家。 (Ah! million lights shine out of great buildings, Ah! There is my home.
Base on the lyrics, The singer has been looking for his home, and at the end he found it, but did he?
萬千燈火透廣廈 is where his home at seem strange, because great city skylines are all over the world, not just in Hong Kong.
Is it possible that Sam Hui like many Chinese use 那 and 哪 interchangeably? I was one of the guilt one, I always wrote "那裏?" instead of "哪裏?"
Is it possible that "那裏是吾家"(there is my home) was intended to be "哪裏是吾家?" (where is my home?)?
Of course, Sam Hui himself would be the best person to answer this question. Since there's no possible way for me to ask him, I wonder did anyone heard him clarify it in some media?
Or more realistically, an official English translation of this song exists, that can answer my question definitely.
Presume 那裏是吾家 did mean "There is my home" we have to interpret the lyrics as the following:
安居似虛話， he was living somewhere he didn't true feel home.
遠處密罩雲霞， his true home is some faraway place he couldn't locate.
何時一朝見霧化，he is hoping the location of his real home would be revealed
子孫歡笑艷陽下。 he and his children will then happily live there
啊！萬千燈火透廣廈， is the description of that heart warming place (Hong Kong)
啊！那裏是吾家。where million lights shine out of great buildings (Hong Kong) is his true home.