If one is with firm good heart but unknowingly serves and follows unjust masters, does one still approach better in samsara?

Good householder,

guṇa means "simply" giving, better goodness. As goodness which leads toward liberation always starts with Sila (moral precepts), certain "goodness" which harms others (at the same time/way) wouldn't lead to freedom of remorse, debt-reduction, liberation... Worldly guṇa is for the most kama-guna, which means "benefiting in regard of sensual gain", and as sensuality causes always others, or oneself, suffering, it's the lowerst kind of goodness if just giving means but harm others by it and it may force attachment to sensuality as well.

Dhamma-guna means giving, goodness, which leads toward liberation, actually for both, oneself and the receiver, if able to take. So maybe good householder is willing and able to take this simple guidance.

For more on guṇa, ggod here: guṇā គុណ - benefactor, string/bound

As for "unknowingly", it protects even in common laws not from punishments, so doesn't it in regard of effects. At least, not to forget, notknowing (avijja), ignorance, is the root cause of suffering and nobody would ever do bad if knowing: "He wouldn't do wrong, if knowing".

I am not sure what you mean by "firm with good heart".

In Buddha's time there were many people practicing asceticism, take for example naked ascetics, they practice asceticism but what is that good for?

"Venerable sir, this naked dog-duty ascetic Seniya does what is hard to do: he eats his food when it is thrown on the ground. That dog duty has long been taken up and practiced by him. What will be his destination? What will be his future course?"[1]

"Enough, Punna, let that be. Do not ask me that."

A second time... A third time Punna the ox-duty ascetic asked the Blessed One: "Venerable sir, this naked dog-duty ascetic Seniya does what is hard to do: he eats his food when it is thrown on the ground. That dog duty has long been taken up and practiced by him. What will be his destination? What will be his future course?"

"Well, Punna, since I certainly cannot persuade you when I say 'Enough, Punna, let that be. Do not ask me that,' I shall therefore answer you.

3. "Here, Punna, someone develops the dog duty fully and unstintingly, he develops the dog-habit fully and unstintingly, he develops the dog mind fully and unstintingly, he develops dog behavior fully and unstintingly. Having done that, on the dissolution of the body, after death, he reappears in the company of dogs. But if his view is such as this: 'By this virtue or duty or asceticism or religious life I shall become a (great) god or some (lesser) god,' that is wrong view in his case. Now there are two destinations for one with wrong view, I say: hell or the animal womb. So, Punna, if his dog duty is perfected, it will lead him to the company of dogs; if it is not, it will lead him to hell." https://www.accesstoinsight.org/tipitaka/mn/mn.057.nymo.html

I think there is another text i can't find where Buddha says that he looked far back and only saw one naked ascetic who had a favorable rebirth and that was due to him teaching the doctrine of cause & effect.

Many Buddhist monks even go to hell, it's all about one's views and Buddha said in pali texts that there is no single thing worse than wrong views when it comes to going to hell.

One good heart is pure love and so pure it can be higher than what you think there's no two ways ONE HEART. that's what SOME people say CHOSEN ONE. They can fall get back up fall get back up fall get back up. For that reason it's because We had to go threw that to have life up and down just like your heart beat if there was no up and down there wouldn't be life.

I am not sure what you mean by "firm with good heart".

In Buddha's time there were many people practicing asceticism, take for example naked ascetics, they practice asceticism but what is that good for?

"Venerable sir, this naked dog-duty ascetic Seniya does what is hard to do: he eats his food when it is thrown on the ground. That dog duty has long been taken up and practiced by him. What will be his destination? What will be his future course?"[1]

"Enough, Punna, let that be. Do not ask me that."

A second time... A third time Punna the ox-duty ascetic asked the Blessed One: "Venerable sir, this naked dog-duty ascetic Seniya does what is hard to do: he eats his food when it is thrown on the ground. That dog duty has long been taken up and practiced by him. What will be his destination? What will be his future course?"

"Well, Punna, since I certainly cannot persuade you when I say 'Enough, Punna, let that be. Do not ask me that,' I shall therefore answer you.

3. "Here, Punna, someone develops the dog duty fully and unstintingly, he develops the dog-habit fully and unstintingly, he develops the dog mind fully and unstintingly, he develops dog behavior fully and unstintingly. Having done that, on the dissolution of the body, after death, he reappears in the company of dogs. But if his view is such as this: 'By this virtue or duty or asceticism or religious life I shall become a (great) god or some (lesser) god,' that is wrong view in his case. Now there are two destinations for one with wrong view, I say: hell or the animal womb. So, Punna, if his dog duty is perfected, it will lead him to the company of dogs; if it is not, it will lead him to hell." https://www.accesstoinsight.org/tipitaka/mn/mn.057.nymo.html

I think there is another text i can't find where Buddha says that he looked far back and only saw one naked ascetic who had a favorable rebirth and that was due to him teaching the doctrine of cause & effect.

Therefore i think if one follows a doctrine thinking, 'by means of this training i will become a Buddha ir i will become Ariya, a Deva or have a favorable human rebirth, if one holds wrong views in regards to this and follows fake teachings then hell is the destination or animal womb.