Transformer isolation and reference
There is a severe problem with that.
Look at the 'live' output from the 220 V source, the one that swings +/- 320 V peak with respect to supply ground. That is connected on negative half cycles through a diode in your bridge to the common/reference terminal between your power supplies, a terminal I suspect you hope will be 'ground'.
The 48 V isolation will give you the same reference, but unfortunately that reference will be swinging between ground and -320 V, dangerous for any grounded test equipment you want to use, and potentially lethal for you.
If you have two 220:48 transformers, then you could run the second backwards from the first one, to get you an isolated 220 V, which would allow both rectified supplies to have a grounded reference.