The difficulty of various subjects depends a lot not just on the subject but on what sort of student you are and in particular how hard you work.
Now I did both Latin and Classical Greek (extensions in both as well) for my HSC so I can say something about these subjects (and hopefully languages in general). Essentially these subjects, along actually with Maths, are skill-based subjects. Essentially the exam is something like, a small portion of the marks come from seen translation (so you translate a passage youve read in class), a bigger portion comes from commentary (so writing essays and long responses about text you've read in class) and an even bigger portion from unseen translation (translating passages you haven't done in class). Essentially most students get very very close to full marks in the first section (you can kinda just memorise the text), and then most students get reasonably marks in the second. Where the massive discriminator is is in the unseen passages - precisely because you can't study for them, rather they're a test of language skills you picked up from whenever you started that language up until that point. I reckon maths is, in a way, a bit similar (although a bigger portion of the subject is purely skills based, and the distribution of skills-based things throughout the exam is very different to in classics) - a lot of questions don't really test your knowledge beyond a very small amount, but instead your abilities. This means that if you're someone who has paid a lot of attention in class from years 7 to 12 and always worked somewhat hard, you're going to have a much bigger advantage in maths and language subjects, because you probably won't be trying to play catch-up with developing skills that are decently slow to develop.
By contrast, English is much, much less of a skill-based subject, unfortunately. You can basically get away with being a pretty poor writer by just writing and memorising essays that are perfect, as many of my friends did. And even if youre not memorising essays explicitly, most people probably are implicitly just by learning the analysis. Having the skills of writing well and reading well are going to help, but you can't just sort of ride on those skills to get high marks. No matter how 'good' you are you're going to have to pull in a hell of a lot of work, and even then youre rolling the dice in the exam with having material to fit the question. Essentially the actual amount of 'skill' you need in an English exam is a lot less than you need in a maths or latin/greek exam, and youre never going to be in the situation where a paragraph of absolutely indecipherable Plato is thrust in front of you to translate - but in other and less obvious ways, its a much harder subject. If youre someone who hasnt properly developed the skills, English wont be as hard in comparison, well because you don't need as much there. But if you have it's still an absolute bitch.
