How to check that I control an address

I recently created a bunch of bitcoin addresses (public starting with 1, PK starting with 5) from a paper wallet, that I downloaded from their github (https://github.com/walletgeneratornet/WalletGenerator.net) and ran offline.

I imported the first PK in my full node, it translated to the pub address I expected and I control this address.

I don't feel comfortable sending coins to addresses I don't know for sure I control. How can I check securely and "easily" that I control them ? Adding all of those PK in Bitcoin core is long and decreases security.

1. Test the windows python code below with the private/public key generated from website. Just to verify the correctness. If correct proceed.
2. Throw coin 256x get your private key.
3. Throw dice whatever, until you get 256 bits.
4. enter the private key in the code below.
5. you should get your bitcoin address.

Code:

# COMMENTS
import bitcoin 
import binascii
PrivKey1 = 'e8ee7398abbbdc8920f53c8fd454e86eab74beae2a9c42d28bf86402f3d87fcb'
PrivKey1Type = bitcoin.get_privkey_format(PrivKey1)
print("Private Key types")
G = bitcoin.encode_privkey(PrivKey1, 'hex',0)
print("Type: hex", G)
G = bitcoin.encode_privkey(PrivKey1, 'hex_compressed',0)
print("Type: hex_compressed",G)
G = bitcoin.encode_privkey(PrivKey1, 'wif',0)
print("Type: wif",G)
G = bitcoin.encode_privkey(PrivKey1, 'wif_compressed',0)
print("Type: wif_compressed",G)    
PubKey1  = bitcoin.privkey_to_pubkey(PrivKey1)
PubKey1type = bitcoin.get_pubkey_format(PubKey1)
H1 = bitcoin.encode_pubkey(PubKey1, 'bin')
print("Public Key")
print("Bin format", H1)
H2 = bitcoin.encode_pubkey(PubKey1, 'bin_compressed')
print("Bin Compressed format", H2)
H3 = bitcoin.encode_pubkey(PubKey1, 'hex')
print("hex format", H3)
H4 = bitcoin.encode_pubkey(PubKey1, 'hex_compressed')
print("Hex Compressed format", H4)
K1 = bitcoin.decode_pubkey(H4)
print("decoded format", K1)
Hash1 = bitcoin.bin_hash160((H1))
print("PubKey Hash from Uncompressed PubKey", binascii.b2a_hex(Hash1))
Hash2 = bitcoin.bin_hash160((H2))
print("PubKey Hash from compressed PubKey", binascii.b2a_hex(Hash2))
BTCaddress = bitcoin.pubkey_to_address(PubKey1, 0)
print("Bitcoin Address", BTCaddress)