You only had to read the initial lines with the letters and the correspondent 'translation'. Then, for each emoji text given, you use this dictionary created to decode it.
You can achieve this using the following Python code:

```Python
from pwn import remote

conn = remote('143.255.251.230', 5555)

alphabet = {}

while True:
rcv = conn.recvline()

if rcv[0] >= ord('a'):
alphabet[rcv[4:-1]] = chr(rcv[0]).encode()

if rcv[0] == ord('z'):
break

while True:
to_decode = conn.recvuntil(b'=> ')[:-4]
print(to_decode)

result = b''
i = 1
while True:
if len(to_decode) == 0:
break
if to_decode[:i] in alphabet.keys():
result += alphabet[to_decode[:i]]
to_decode = to_decode[i:]
i = 0
i += 1

print(result)
conn.send(result + b'\r\n')
print(conn.recvline())
print(conn.recvline())

conn.close()
```