5E/A5E cantrips, feats, and multiclassing question

Hey everyone.

I have a player in my a5e game who's thinking of doing a Traveller Sorcerer with some healing spells. That player is hesitating between a feat which would let them choose spells from another class, or perhaps multiclassing. Their main question which I assume would help them make up their mind is how do cantrips grow alongside your character if they come from a different spell list.

Now I know both game are 90-ish plus similar, which is why I also ask the question for regular 5e as it could, at least, help me figure out an a5e equivalent answer... The multiclassing and spellcasting sections of a5etools (don't worry, this one is not piracy, it's owned by ENWorld) were pretty much silent on the subject of cantrips progression. I could search that other site with a very similar name (which will remained unmentioned as it is technically piracy), but if they explain both sections in the same way a5etools does, I'll be left with the same non-answers concerning cantrips potency at later levels...

So here is my personal and potentially wrong interpretation: cantrips use your total character level to determine their potency. This seem like the only answer which makes sense to me, otherwise, all those cantrips-granting feats would become near-useless, especially at later levels.

So is my interpretation correct? If not, what is the real answer? Have any of you asked this or a similar question to Sage Advice or some sub-reddit?

Burn the character at the stake and never worry about it!!!!

If not well, yeah, Cantrips have used your full characters levels if in not the same class in 5e. I think in a5e that would be fine too.

Tried finding an answer for you on another website that shall remain nameless, and I came up short. I'd say go with your ruling.

D&D 5e cantrips use the total character level, when they reference level increases. This is documented in the latest version of the 5e Players Handbook in the Multiclassing > Spellcasting section.

While this wasn't specifically asked, another aspect to help make a decision is whether or not the character must use a different spellcasting ability. As an example, if a sorcerer's spellcasting ability is Charisma and they decide to multiclass into cleric, their cleric spells will use Wisdom. Some feats follow that same requirement, but there may be other feats or class features that retain the primary ability.

CancerMan is spot on.

I would point out, in addition to potentially using a different casting stat, the nature of the spells may require a different focus.

Some items and classes in 5E provide workarounds, but it is something to consider.