So in accordance to what you are saying some seed phrases are easier to guess than others.

In the Ian Coleman Mnemonic, you can check entropy details.

Time To Crack
centuries
Event Count
63
Entropy Type
hexadecimal
Avg Bits Per Event
4.00
Raw Entropy Words
21
Total Bits
252
Filtered Entropy
1fd2f279505c87ecf83b09042c0a032021abfdf566eb2ea38a09a90123ed4bc
Raw Binary
00011111110 10010111100 10011110010 10100000101 11001000011 11110110011 11100000111 01100001001 00000100001 01100000010 10000000110 01000000010 00011010101 11111110111 11010101100 11011101011 00101110101 00011100010 10000010011 01010010000 00010010001 11110110101 0010111100


Are you saying that :
1) this is not big enough entropy?
2) this is enough entropy but with JS, thiere can be bugs?
3) other things?