non ritual spells of level 50.

so,the core rulebook says, that "only rituals can be over 50"
which implies that normal spells can be up to and including 50.
yet..all level 50 spells are rituals. was there a writer mistake?

There's "Last Flight of the Phoenix" on page 37 of HoH:S, which is level 50 without being a ritual.

Looking solely at the corebook, there don't appear to be that many level 50 spells at all. Of those that there are, "Calling the Odious Drought" has a boundary target, as does "Illusion of the Misplaced Castle", so they're rituals for reasons other than level. That just leaves Rain of Oil, which is a level 50 ritual without an explicit reason for being so. It could be a mistake, or it could be that the author decided it came under "ritual due to being a major effect" but didn't spell that out.

Actually, there are plenty of them in the core book, just hidden. Most (probably all) of those TeFo Gen spells could be taken at level 50. So, for example, Wind of Mundane Silence lvl 50 is a non-ritual spell.

then why are there these spells of level 50 with target less than boundary and duration less than year... that are classified as rituals?? is it a mistake?

Which spells in particular? Some are rituals because of their guidelines. Some are rituals because of their extreme effect. Some are rituals due to being somewhat non-Hermetic and having been integrated.

Look at Sight of the Sigil in HoH:TL on page 75 for another example of a non-ritual, written as level-50 spell.

RAIN OF OIL for instance. page 128 core rulebook

Rain of oil does include a +5size modifier - any spell involving huge size can be made a ritual at the Storyguide's/book editor's discretion. See "Breath of the open sky" on page 126 for a level 40 spell that is made a ritual because of the spectacular effect.

Just to clarify: it's not just "huge size", it's about having a sufficiently "powerful" effect. See p.115 of the corebook (emphasis mine):
"Spells requiring rituals are those that fall outside the categories listed for formulaic and spontaneous spells described under “Ritual Spells” on page 114. Certain powerful spells and spells inherited from the Cult of Mercury are also Ritual spells. Storyguides should use their discretion in declaring other spells Ritual.".
Basically, a troupe can declare a Ritual anything that it feels would be "too mighty" for a magus to produce at will with just a flick of the wrist. Affecting very large areas often qualifies, but is neither a necessary nor a sufficient condition.

Another example is CURSE OF THE RAVENOUS SWARM (CrAn 50), which came up in discussion recently.

Looking back at these core spells, I'm struck by how effects that the corebook considers worthy of ritual seem less impressive compared to more recent published material or to magics discussed in this forum. There's been a good deal of power creep over the years.

Forum, maybe. When discussing how to get lots of "oomph" from simple spells there's a tendency to overlook the "lots of oomph = ritual" principle (I've been guilty of this myself).

But I'd be curious about published material. Can you find a published Ritual that's less "impressive" than a published non-Ritual? I can find some borderline cases (often in sections that have much more blatant violations of the spirit or letter of the rules, e.g. the Tremere spell section in HoH:TL) but nothing really blatant. Uhm. Save perhaps the flying castle of Legends of Hermes, but that's one chapter with rather poor mechanics.

I didn't really mean that specifically in terms of the rules for Ritual spells, but rather in the general sense that things considered "impressive" in the core book, such as swarms of insects or big storms, don't seem like such big deals compared to such things as building continents in the middle of the Atlantic, recovering souls from Purgatory, or preventing the end of the world.

We've gone from Tales of Mythic Europe to Tales of Power to Dies Irae. It's the normal trend for a role playing game, I suppose.