Hello everybody! I am making this thread because I got two small salvia d. plants recently and one of them seems to be dying whereas the other seems to be fine (although it hasn't been growing much). I'll post a brief overview of the state these plants were in when I got them and what I did so that you may come up with a course of action. Thank you to those who take the time to read through this post

Some pics will be at the end as well.
I ordered two little Salvia plants about 20 days ago. They arrived quickly (3-day shipping). The seller had placed each of the plants in a little disposable pot with a humidity tent (some plastic bag around the plant held by Scotch tape). The soil the plants were in was EXTREMELY wet. Literally dripping, soaked, you get the picture. I bought two large pots and some soil meant for in-house plants (the bag said the soil had good drainage, which seems to be the case, and a slightly acidic pH).
I transplanted the two little plants. One of them seemed to be doing well, it was not wilting as much as it had been when it arrived and nowadays it's not wilting at all. The other one... was and is in a pretty rough shape.
The thing is, this other plant consisted of a thick main stem (12 cm long) that had clearly been cut at that height, as I could see the hollow part and look inside the plant. From this main stem, two side-stems were growing, looking OK with quite a lot of leaves. The main stem was like woody and dried from the top up to the middle of it, except on the side of the square from where the side-stems were growing, which were green around the bases.
Sadly, some of the leaves of this plant have been somewhat wilting for quite a while. The plant developed brown/yellowish tips over the days on most of its leaves, but I thought it would get better. The situation got much worse just a few days ago (15 days after I received them). Most of the leaves became 20-30% brown/dead from the tips (see pictures). The rest seem fine with only a slightly yellowish/brownish tip, but I fear they will also go down this route and maybe die.
These plants receive indirect sunlight during the morning and up to 4 PM (they are on the main room of the apartment with a large window facing east; I live in a small apartment on the 9th floor facing the sea). I water them every three/four days; I usually try to feel the soil near the roots to see if it's becoming dry and only then water them with either collected rain water or tap water that was boiled and left to cool down. I mist them occasionally throughout the morning and midday, when the apartment tends to become really hot. I sometimes move the pots closer to an open window so that they can get some fresh air (the sun still never shines directly on them, but pretty close). After two weeks or so of receiving the plants, I added a little bit of chemical fertilizer to the soil (one that you dilute in water before watering). I had done this to my purple Salvia Guaranitica plant, which I maintain under the same conditions, and it started to grow at an incredible rate and looks healthy as ever.
What should I do?! Please check the pictures and tell me if I should remove the large sick leaves so that the plant focuses on the little ones, if I should water less/more, if I should let them have some direct sunlight at least during the early morning, if I should do something about the gaping hole on the stem, if I should check for root rot/stem rot, if I should cut the dead parts of the leaves, or if I should just let the plant be and see what happens. None of the two plants seem to be actively growing much; there are some little leaves that seem to grow veeeeeery slowly. The healthy plant has very recently (3 days ago) also developed some blacking at the tip/sides of some of its leaves, so please check that too and tell me if something should be done about that too.
THANK YOU SO MUCH if you took time to read this and have some advice for me. I would have posted this in the Salvia subforum but I am not an active user yet.
One pic of the healthy plant and three of the sick one:



