Here's how I parse the sentence you've got:
For the first half, I think your translation is decent.
But to do it slightly more literally:
= It would be better if your actions were more planned.
したほうがいい → "It would better if" / there are other constructions that express "should" more directly.
計画的 → you've translated this as systematically, but I think in context it makes sense to more directly express "plans"
For the second sentence, I think the basic sentiment is all ぼかし表現 (things to soften the previous sentence).
Going through it piece by piece,
- 私も - I think here the も is because the previous sentence is criticism of the other person, so here the speaker is indicating that they also have will criticize their own self.
- 他人のこと - I don't think this is "other people" but rather "other people's stuff" / "other people's matters" / "other people's junk"
- は言えない - I think the reason why there's a は here is that the preceding part of the sentence is the sort of thing that the subject feels is a character flaw they should improve on. While literally "I can't really talk", I think the sense is "I shouldn't really talk" or "it's not my place to talk about "
- けどさ - I think this けどさ is not a real attempt at conjunction, it's an attempt to soften the sentence
So I put the second half together as "But I am not really someone to talk about other people's issues." (the wording might be too American -- the point being "I've got issues too -- like talking about other people -- so I'm going to shut up now").
Or at least that's my sense. If I'm wrong I hope to learn how to do better by getting comments or corrections.
I think the も is to say sentence 1 criticizes あなた and sentence 2 is criticizing 自分
I think the は marks off what the problem is with the speaker (talking about other people's issues) rather than being something where it would make much sense to view it as a substitute for を or が.
But I take the entire point of the second sentence to be: I just said something sharply critical about you, so now I'm going to try to soften that with a "we all have problems and here's one of mine."