In its current state, the Changeling role's first objective to take a certain amount of DNA from x amount of crew.
This means killing them via husking.
That is generally where people stop reading into the role, and go on their merry way killing and murderboning for the rest of the round.
At round end they will have failed the rest of their objectives - because heck, all they really did was spend the round killing crew.
In its current iteration, the Changeling role is a free license to indiscriminately kill crew, or grief the station by trans-stinging the crew into Vox.
Coupled with the fact that there is no way to tell who is a Changeling to start with (short of having been attacked by one yourself), Changeling rounds are not fun.
My suggestion to balance out the Changeling role, being that it is a murder role at its basis, is to simply strip away the rest of the objectives.
Nobody is doing them anyway, and as they have a free license to grief the rest of the crew at current, the role might as well face more towards that direction.
Give Changelings a bar which ticks down over time, and can only be refilled via husking.
If a Changeling fails to refill this bar to maintain their 'humanoid' form, have them devolve into a monstrous, obvious form as a huge red creature with blade arms.
Since the role revolves around murdering crew, it would serve much better if the Changelings had some ultimatum, or reason to be doing so.
My biggest complaint with the Changeling role as it currently stands is that they are night on, if not completely undetectable.
Their stings don't generate text, they don't have any detection method such as flashing eyes, burning in the chapel, or the injuries apparent to culties.
A Changeling is completely invisible while they freely murder whoever they please - simply because there is no way to detect them.
A handcuffed Changeling can even continue to freely use its proboscis and sting abilities on the officer who is dragging them.
Additionally, Changelings are exceptionally durable, and can clone themselves even if they do happen to take lethal damage.
In its current form, the Changeling role is an open invitation to grief, and there is next to nothing the rest of the crew can do except wait for the shuttle.
To summarize my suggestion, and the source of my salt, if Changelings are going to continue to be played as such, they could use a lot of tweaking to be geared more towards the murderboning role they currently are being used to play in the round rotation if Changelings a.) had some reason beyond objective 1 to be killing all of the people that they are, b.) were held accountable for excessive crew killing beyond objective 1, and c.) had some form of detection available to the security staff who have to deal with all of their nonsense, including the ability to see the proboscis text that would make the role more challenging for the murderboners who are currently giving it a bad name.
It's just not fun at all to deal with for new players, or experienced SS13 players.