Is propane-1,2,3-tricarbaldehyde the correct IUPAC name of CHO-CH2-CH(CHO)-CH2-CHO?
From the Nomenclature of Organic Chemistry: IUPAC Recommendations and Preferred Names 2013, let's cite one of the rules for usage of the -carbaldehyde suffix, the relevant one:


  P-66.6.1.1.2 The suffix ‘carbaldehyde’ is used when more than two $\ce{-CHO}$ groups are attached to an alkane.
  
  Example:
  
  $\ce{OHC-\overset{1}{C}H2-\overset{2}{C}H(CHO)-\overset{3}{C}H2-\overset{4}{C}H2-CHO}$
  butane-1,2,4-tricarbaldehyde (PIN)


Thus the correct name is propane-1,2,3-tricarbaldehyde.