Does the caster of Steel Wind Strike trigger effects based on the position they attack from or to?

Question

The spell Steel Wind Strike (XGE, p. 166) says:

You flourish the weapon used in the casting and then vanish to strike like the wind. Choose up to five creatures you can see within range. Make a melee spell attack against each target. On a hit, a target takes 6d10 force damage.

The range is 30ft, so that would make any creature in a 30 ft circle* around you a valid target, in theory.

But a bunch of scenarios I can think of, that hinge on whether the attacker is moving between strike to be next to the creatures or not, hopefully by listing them all I can shake out an understanding of what is happening.

Also for reference, I'm aware of the question asking Do you get advantage on the Steel Wind Strike spell's attacks because you "vanish"? as well as Do Steel Wind Strike's attacks have advantage or disadvantage against distant prone targets? but I think some of these examples might require a different answer.

What if any are the side effects of these situations?

• Targeting a creature inside the area of an Alarm Spell (Basic Rules , pg. 211), without starting or ending up inside the area - set the alarm off or not?
• Targeting a creature 5 foot inside the range of a caster who knows Temporal Shunt (so that all squares around the target are in range but you are not.), even though you start and end outside of range - the Steel Wind Striker can be targeted or not?
• You have Crusader's Mantle (Player's Handbook, pg. 230) and the aura would overlap with a non-hostile who readied to make an attack as a reaction, but only 'during' the attack not before or after - the readied attack gets the damage bonus or not?
• Targeting a creature with Fire Shield (Basic Rules, pg. 242) or Shadow of Moil (Xanathar's Guide to Everything, pg. 164) if it starts and ends 5ft or 10ft away- those spells can lash out with fire or shadow or not?
• Targeting a creature within 5ft of another creature with the Sentinel feat. but not starting or ending in range of the Sentinel - the sentinel can make an attack as a reaction or not?

For the sake of clarity, I'm not talking about the situation where the caster of Steel Wind Strike starts or ends that spell in range of, or inside the area of the above effects/spells, but where their targets are inside some area or range.

These feel like they cover a lot of the fundamentals for what can react to the attack from a Steel Wind Strike. It also differentiates between the vanishment being visual (similar to invisibility) or physical (perhaps similar to being ethereal/spectral but less well defined).

Does this tell us anything about the position of the caster of Steel Wind Strike when they make each attack?

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*: Or your metric's** equivalent
**: No, not the metric system, the Distance Function

Answer 1

Range is only relevant when the spell is cast

The target of a spell must be within the spell's range.

Once a spell is cast, its effects aren't limited by its range, unless the spell's description says otherwise.

If the target is within range when you cast the spell, it’s a valid target. It doesn’t matter if you or they subsequently move out of range.

Notwithstanding …

There is nothing in the wording of Steel Wind Strike that suggests the caster moves at all. They make melee attacks but it doesn’t say they move to make those attacks. So they don’t.

Answer 2

These cases are all affected by range. For all except the case of Temporal Shunt, the distance the Steel Wind Strike caster is away from the target matters highly.

• The Alarm spell would not trigger because no creature is entering the designated area (assuming the caster stays outside of the designated area when casting Steel Wind Strike). The spell only triggers if the caster enters the designated area for some reason.
• The spellcaster that cast Steel Wind Strike can be targeted by Temporal Shunt in practically all cases because the range of Temporal Shunt is 120 feet, much larger than that of Steel Wind Strike.
• The bonus damage of Crusader's Mantle would still function. If the creature makes an attack as a reaction, and hits with the weapon attack, Crusader's Mantle explicitly allows it to add the extra damage ("when it hits with a weapon attack"). Of course, if the Steel Wind Strike caster stays out of range of a melee attack reaction, then the creature wouldn't get to make one in the first place.
• Spells like Fire Shield do get triggered, as long as the caster is within 5 feet, because Steel Wind Strike explicitly makes a "melee spell attack" and Fire Shield triggers on a "melee attack" (which includes melee spell attacks, as per PHB 195).
• By the same logic, the Sentinel feat is also triggered, as long as the caster of Steel Wind Strike is within 5 feet.

For the most part, anything that triggers on a "melee attack" also triggers on the melee spell attack made by Steel Wind Strike. However, if the caster stays as far as possible away, it can no longer be targeted by many of these, because most specify a relatively short range. For example, it can no longer trigger Fire Shield and Sentinel.