I’d say what you have works as a general feel for what he’s saying. There is a bit of difference in nuance, however.
Further writing on this, with some considerations, and my try at a translation.
Kazutaka is saying Kanami keeps adding 「面倒ばかり」, nothing but trouble.
I’ll admit, I haven’t looked at depth into the particle ばかり, so I lack the intuition of grasping the nuance between the various English translations given in a dictionary (“only, merely, nothing but” and “always, constantly”).
I read this along the lines of “you’re doing nothing but adding bother”, “you’re just being more and more of a bother”. The やがる adds contempt to the statement.
Since the first word balloon ends in the connective て (similar to “and” in English), I think this is a case where the two word balloons are one single sentence. (I know, this is exactly the opposite of my prior reply, where the first balloon ending in な signified to me that those two word balloons were two separate sentences.)
Thus, I read the whole as being along the lines of (loose translation):
“You’re just being more and more of a bother, and you’re an eyesore.”
Or if we play even looser with the translation for something that flows better in English and still conveys the general dialogue:
“Geez, can’t you do anything right? You’re such an eyesore!” (I did break it up into two sentences here, because I felt that had a better flow in English.)
I've been caused/let/made to write a bit here, so I'll collapse it as well.
Disclaimer: I’m not familiar with the level of detail covered in Wasabi (based on your quoting). I’ve landed on Wasabi pages from time to time, and have had a positive view of what I’ve seen from them.
Disclaimer 2: This also means I’m learning along the way as I write, so hopefully everything below is correct. (I’m still a learner!)
According to this very much fully Japanese grammar site’s page on causitive:
(I’ll go into what this means in a moment.)
The site gives a sentence:
「妹が買い物に行く。」 “My sister goes shopping.”
Here, “sister” is the subject, the one doing the action of “to go”.
The grammar site gives the exercise of changing the sentence to “My mother lets my sister go shopping.”
In this new sentence, the one doing the action is the mother. The mother is letting someone do something, so the mother would be marked by が.
「母が妹〇買い物に行かせる。」 “My mother lets my sister go shopping.”
So, what do you mark “sister” with? For now, I’ve just stuck a 〇 in there were a particle needs to be.
According to the grammar site portion quoted above, because the verb 行く is a self-move (intransitive) verb, the noun “sister” becomes a modifier marked with を.
「母が妹を買い物に行かせる。」 “My mother lets my sister go shopping.”
Note that this can also be “My mother makes my sister go shopping.” This form has an overlap of letting and making. In either case, it’s the mother that causes the sister to go shopping.
The site also says that when the verb is an other-move (transitive) verb, the noun that the subject causes to do something is marked by に.
「弟が窓を閉める。」 “My brother closes the window.”
「母が弟に窓を閉めさせる。」 “My mother makes my brother close the window.”
You can think of the latter as “My motherが causes the windowを to be closed by my brotherに.”
Let’s bring this back to レンタルお兄ちゃん now.
If you are saying “my hand slipped,” you might say:
Here, “(my) hand” is the subject. It’s the one that slipped. You grabbed for something with your fingers, and it slipped between them and fell from your intended grip.
However, if you say, “I caused my hand to slip” or “I let my hand slip”, essentially saying you are the one responsible for causing that to happen, then you would be the が-marked subject. You did the action of causing.
When saying “I let my hand slip”, the speaker is the subject marked by が, in which case the subject is typically not spoken.
I put 〇 where the particle should be. We know it can’t be が because が marks the subject, the one who caused the hand to slip. So what particle goes here?
According to the Japanese grammar site I quoted from, if the verb is self-move (intransitive), then the particle を gets used here.
Let’s see if the World Wide Web agrees with 手を (versus 手に which would be for an other-move/transitive verb):
All this has been me learning in real-time so far. Now let’s circle back to the original question:
The particle を marks an object. An object is what the subject is doing the action of the verb on or to. Here, the verb is “making slip”, “letting slip”, “causing to slip”. The subject causing it is Makoto. What is the object that Makoto doing the causing of “causing to slip” to? His hand, 手. This, 手 is marked by を.
One thing that CureDolly teaches is more or less that when a verb has a helper verb, we need to take the helper as the main verb. Seen that way, the preceding verb is a modifier of the helper verb, the same as every other modifier works in Japanese. In this sense, the main verb is られる (to cause). You can cause all kinds of actions, so we modify this with a verb to specify what action we are causing: 滑られる.
I’ve never seen this concept mentioned outside of CureDolly. I haven’t really read much in the way of Japanese native material on grammar to know what they say about the causitive form. (The page I linked to above is one of the few pages I haven’t yet read on that specific native Japanese grammar site.)
That said, if we use CureDolly’s view, considering the helper verb as the main verb of the sentence, then I feel all the particles make perfect sense.
In this case, we have the verb 滑る, and attached to it is the helper verb られる. If you try to work out the particles from the perspective of 滑る, it becomes confusing, because the subject is not doing the verb 滑る. The subject is doing the verb られる (causing an action, essentially), so the particles are from the perspective of られる.
Viewed this way, we can see that を properly marks the object of the action, as the action is られる.
If I were translating, I might go with:
「今のは手を滑らせた」 “As for right now, I caused my hand to slip.”
But that sounds odd in English (too Japanese), so if I work it out into what would be more natural English (even though it deviates further from how the Japanese grammar works), I’d go with:
“I let it slip from my hand.” (Implication: I should have been more careful.)
I’m starting to think I’m bad at giving small answers.