s///eg and the hash table disguised as an array, plus basic bamboozling with difficult characters. In a more transparent form ...

%_=(62 => 20,
    38 => 1,
    35 => 50,
    33 => 2,
    60 => 10,
    37 => 5);

#  Match each chunk of optional characters in a specific order
#  Look up the ASCII values of each char in the chunk in the hash
#  Add the hash values plus a starting value of 30
#  Replace the chunk with the character whose ASCII you just added up

# (Pattern modified to add \s* so that chunks could be 
#  formatted prettily)

s:#*>*<*%*!*&*\n*\s*:
  $;=30;  $;+=$_{+ord}  for split'',$&;  chr$;  :eg

for

$_=q:>>!!
     #><%&&
     >>>>%
     >><<<<%&
     !
     #<%!
     #><
     >>><<&
     #<<<!&&&&
     #<<!&&
     >>>%%&
     >><<%%%%&&&&
     !
     >><
     #>&
     >>><<!!
     >>>%%%&&&
     !
     ><<<<<&&&&
     >><<%!
     >><%%%&&&&
     #>%&&
     >>><&
     >>>>&&&&:;
print;
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PS Did you get the idea for hiding the newline from your critique of my JAPH?