1. Translate from Braille to get `5a42545a42485a42495a42534253457a6361774253457a797a7561776163 and unhex for ZBTZBHZBIZBSBSEzcawBSEzyzuawac` and unhexlify for `ZBTZBHZBIZBSBSEzcawBSEzyzuawac`
2. reading the source, "\_" gets replaced with "CTF" before the mixing step, so we can guess the "BSE" in the mixed flag is "CTF" shifted by 25
3. to get the value for `numShift` we can calculate 25+26 (since CTF is uppercase) = 51, `chr(0x41+51)` gives us "t"
4. reverse the `mix` and `puzzled` functions, I opted to do this by editing the provided Python script:
```
import string

upperFlag = string.ascii_uppercase[:26]
lowerFlag = string.ascii_lowercase[:26]
MIN_LETTER = ord("a")
MIN_CAPLETTER = ord("A")

def reverse_mix(oneLetter, num):
if oneLetter.isupper():
index = upperFlag.index(oneLetter)
shift_index = ord(num)-MIN_CAPLETTER
return chr(MIN_CAPLETTER + (index - shift_index)%len(upperFlag))
else:
index = lowerFlag.index(oneLetter)
shift_index = ord(num)-MIN_LETTER
return chr(MIN_LETTER + (index - shift_index)%len(upperFlag))

def reverse_puzzled(puzzle):
original = ""
pos = 0
while pos < len(puzzle):
if puzzle[pos:pos+3] == "CTF":
original += "_"
pos += 3
else:
if puzzle[pos].isupper():
index = upperFlag.index(puzzle[pos])
index2 = upperFlag.index(puzzle[pos+1])
index3 = upperFlag.index(puzzle[pos+2])
binary = "{0:05b}{1:05b}{2:05b}".format(index, index2, index3)
original += chr(int(binary, 2))
pos += 3
else:
index = lowerFlag.index(puzzle[pos])
index2 = lowerFlag.index(puzzle[pos+1])
hex_val = "{0:01x}{1:01x}".format(index, index2)
original += chr(int(hex_val, 16))
pos += 2
return original

mixed="ZBTZBHZBIZBSBSEzcawBSEzyzuawac"
numShift="t"
unmixed=""
for count, alpha in enumerate(mixed):
unmixed += reverse_mix(alpha, numShift)
print(reverse_puzzled(unmixed))
```

This prints `THIS_is_easy` and the flag is TUCTF{THIS_is_easy}