You can use the cntlout= option to copy all existing formats to a SAS dataset. This can be distributed for review or stored as a backup. It can be exported to Excel for amendment and then imported back into SAS. There are a lot of columns but the main ones to review are called start and end, the start and end values for a range covered by a single formatted value. Additional rows can be entered if required. The modified table can then be read back into proc format using cntlin=. Make sure no-one has renamed any of the columns.
Proc format cntlin=work.formatlist ; quit ;
You can also create a cntlin table to add a new format into the library, from a lookup table in the database. At a minimum you need to define s start column, a label column to hold the formatted value, and a fmtname column as the name of the format. A HLO column is often useful to define how the format will handle out of range values.
Richard