We are talking about what is perceived to be the inappropriate use of coloured fonts here - not the trolling rules in general, or other forms of what is perceived to be trolling. You should stick to your own topic lest you muddy the water.
I think it would be difficult for Jagex to draw a line and advise the FMods what might or might not constitute 'trolling' in regard to the use of font colours.
People perceive colours in different ways - what is an eye-watering and unpleasant shade of screaming green to one person might look quite charming to someone else.
Also, monitors reproduce colours differently; a warm shade of pink might come across to some as loud, garish and uncomfortable.
It's very subjective and also influenced by technical factors.
So where would Jagex draw their line? Remove use of coloured fonts? That's a step backwards. Only allow a prescribed list of pastels? Again, a retrograde step for these forums.
I appreciate that there are, indeed, a handful of persons just lately who are, possibly using the facility Jagex gave us in an attempt to be annoying. They might actually be ignorant of their actions but for the sake of argument I'll assume they are being quite deliberate about it.
To me, the easiest way to deal with it without asking Mummy to step in and take our toys away is to boycott interaction with those posters. Having no one respond to them will soon become boring for them. Trolls usually troll to get attention/a reaction, I believe. So don't feed them.
Or, we could be even more grown up about it and actually ask said poster(s) why they are using a generally (to the majority) repulsive/unattractive form of posting. They may, after all, be oblivious to their actions.
Well there's been a response from the one person I approached. Essentially it boils down to ignoring my post and continuing to post in an eyeball-piercing colour with no regard for anyone else. So it is my belief that he, at least, is being deliberately unpleasant. Trolling, if you like.
I'm not at all sure that a report to FH would produce any results given that the use of colour - any colour to any extent - isn't actually against any Rule that I'm aware of. However, I'll give it a shot.
It would seem the only recourse left open to anyone who finds such posting an unpleasant experience is to ignore posts by that individual - starve him/her of the attention they are so obviously craving.
I actually wouldn't put myself to the two second bother of scrolling over their text in order to render it readable - the courtesy of them toning down their use of colour is not afforded to me, by them, so I will offer no courtesy myself.
It's a sad state of affairs, really, and speaks volumes of the character of the poster who knowingly makes every post with the sole intention of making the lives of others just that little bit less enjoyable.