The password to the test encryption contains a mix of 19 chars lower case letters / Upper case letters / numbers / and a few non alphanumeric chars. No reference to any word in any dictionary. The only way to crack it is via bruteforce in tens of years,
With modern technology, it will take a lot longer than tens of years to crack the password you describe. For all intents and purposes, the password will not be broken.
1.
I have wallet1, where seed and xprv are both encrypted with strong password, I can see the balance and it's gianormous by anyone's standards. Wallet1 cannot be cracked by nothing, dictionary and bruteforce are out of the question. Possibly bruteforce, but length of password is unknown, and I'd like to be realistic and not go that route which will lead to alot of time wasted and eventual disapointment.
In order to have any realistic chance of bruteforcing the password, it would need to be no longer than 12 characters in length, or with there being 12 unknown characters of the password if you know a portion of it.
If the wallet has ever been saved unencrypted on a device you have access to, you may be able to recover a portion of the seed or xprivkey using forensics software. If this is true, you should unplug the device immediately, and use a separate device to research how to best use computer forensics (most likely employing an expert) to look for a portion of the seed. If the unencrypted wallet was on a device a long time ago that has been used extensively in the meantime, it is unlikely you will recover any part of the seed/wallet file.
IMO, your best bet is to narrow down the password by obtaining a portion of the description of the password, such as that it starts with 'abc', ends with four numbers, or anything else you can obtain/remember, and brutforcing the password with these assumptions narrowing down the possibilities.