Try replacing two functions in the trem_hintstring.gsc with these:

setHintString_fixed_thread(string)
{
	self notify("new_thread");
	self endon("new_thread");
	if(!isDefined(string)) return;
	tokens = strTok(string, " ");
	end = false;
	leftstring = "";
	rightstring = "";
	for(i=0;i<tokens.size;i++)
	{
		if(tokens[i] == "&&1" || tokens[i] == "F" || tokens[i] == "[{+activate}]" || tokens[i] == "[Use]") //use key will be added by the menufile
		{
			tokens[i] = "";
			end = true;
		}
		if(end) rightstring = rightstring + tokens[i] + " ";
		else leftstring = leftstring + tokens[i] + " ";
	}
	players = getPlayers();
	while(isDefined(self))
	{
		for(k=0;k<players.size;k++)
			if(players[k] islookingatent(self) && (distance(players[k].origin, self.origin) < 75) || players[k] isTouching(self))
			{
				self.leftstring = leftstring;
				players[k] thread setHintString_show(self, leftstring, rightstring);
			}
		wait 0.1;
	}
}
setHintString_show(trig, leftstring, rightstring)
{
	if(isDefined(self.lookingattrig) && self.lookingattrig == trig) return; //no need to keep calling the thread if we're still standing at the same trig
	while(isDefined(trig) && leftstring == self.leftstring && (self islookingatent(trig) && (distance(self.origin, trig.origin) < 75) || self isTouching(trig)))
	{
		self.lookingattrig = trig;
		self setClientDvar("trem_hintstring_left", string(leftstring));
		self setClientDvar("trem_hintstring_right", string(rightstring));
		self setClientDvar("trem_hintstring_vis", 1);
		wait 0.1;
	}
	self.lookingattrig = undefined;
	self setClientDvar("trem_hintstring_left", " ");
	self setClientDvar("trem_hintstring_right", " ");
	self setClientDvar("trem_hintstring_vis", 0);
}

That's because I wrote self instead of players[k]. I don't follow what you are saying fixed it but try changing

self.leftstring = leftstring;

to

players[k].leftstring = leftstring;

first.

Ah, I jus tnoticed that I had forgot to change "self endon("new_thread");" to "trig endon("new_thread");" in the sethintString_show() function. Try making that change and see if it fixes that issue.

if(isDefined(self.lookingattrig) && self.lookingattrig == trig) return; //no need to keep calling the thread

Alright, thanks. Wiki updated to v1.3.

You forgot the isLookingAtEnt(ent) function in the source code. xD

Bug Report: Having a thing for the USE key like "&&1" causes the hintstring not to update until you walk away from the trigger than towards it.

Maybe because I only check the left side of the string. Please write the full hintstring you are using and what you are changing it to.

trig _setHintString("[Hintstring A] Press &&1 This is hintstring number: " + level.hintstringtest + "!");

players[k].rightstring = rightstring;

players[k].leftstring = leftstring;

while(isDefined(trig) && isDefined(self.leftstring) && self.leftstring == leftstring && (self islookingatent(trig) && (distance(self.origin, trig.origin) < 75) || self isTouching(trig)))

while(isDefined(trig) && isDefined(self.leftstring) && self.leftstring == leftstring && isDefined(self.rightstring) && self.rightstring == rightstring && (self islookingatent(trig) && (distance(self.origin, trig.origin) < 75) || self isTouching(trig)))

Also small question. Does use up any limits? Not sure hud.menu counts as towards the hud limit.