Abuses will exist wherever oversight is insufficient.
Planning to remain in Japan after reaching the age of 'no longer able to work' is a condition that permanent resident visa, if the proposed changes actually occur and persist, may no longer provide. Given that, then contributing to the national retirement/pension plan and preparing for naturalization would seem to be the proper route to that long term expectation of reciprocal security.
If the job pay is 'lower than a Japanese worker would accept' then that does indeed classify as abuse of the SSW1 designated rules. As they have been explained to me by legal council, SSW1 rules state explicitly that employees must receive at least as much pay as would cost for a local laborer, in order to not depress local labor values.
If this is the condition that you or persons known to you are working in, that is a reason needed for a change in employment.
A JLPT test is not typically part of the SSW2 requirement, at least for the industries I have studied the test material for, but the tests are in Japanese at about JLPT4/3ish level. Each tests specific vocabulary (the kanji portion) are very specific and one can focus on learning the necessary content which is a much lower threshold than JLPT3, but studying for that does become dependent on the work-life balance aspect. Clear communication with an earnest and fair employer is important for establishing that; and it sounds like you are having some difficulties with this side of things. That is unfortunate.
I don't have any magic tricks for not getting taken advantage of; but know that it appears your experience with the SSW1 is not necessarily typical of the program as intended, and there may be some alternatives to feeling trapped or not valued in the long term here.
Is your 登録支援機関 (tōroku shien kikan) Registered Support Organization an active participant in the necessary oversight, or have they effectively been rubber-stamping the actions that have led to this situation?
That was where I was leaning on the socialization aspect. The RSO has some responsibility in making sure SSW workers are aware of the scheduled community building events in order to facilitate socialization and acculturation - these can always be done independently, but there's an obligation to facilitate these for the RSO.
Having active opportunities to interact (again work-life balance) can be a big help in working toward fluency, which I feel should be a goal for anyone planning a long term habitation in any country. In Samoa this is fa'asamoa, "Fesili muli mai ia mua mai" when arriving follow who came first, the "When in Rome do as the Romans" and in Japanese 郷に入ってはば郷に従う go ni iteba go ni shitagau.
If there is anything you think I might be able to do to help, I am willing to try. もし手伝う事があれば遠慮なくネ