akĉento

This is not a spelling variant of akcento. It is a sense split, and the dictionaries say so. Akĉento means one thing only: the accent somebody speaks with, the way a voice announces where its owner is from. The Reta Vortaro defines it as a manner of pronunciation departing from the standard, local or national, by which one recognises a foreigner or somebody from another region - and gives nothing else. Akcento covers the other jobs: the stress on a syllable, which in Esperanto always falls on the penultimate, and the emphasis you put on a word to insist on an idea.

And the split runs both ways, which is the part worth knowing. ReVo's akcento entry does carry the way-of-speaking sense as a third reading - and tags it arkaismo, an archaism, pointing you at akĉento instead. So the two words are not interchangeable in modern writing. Somebody's Groningen accent is an akĉento; the beat in ak-CEN-to is an akcento. If you have been using one word for both, this is the page that fixes it.

Two honest caveats. The first is that plenty of fluent speakers do use akcento for both, because the doublet is invisible until somebody points at it, and you will be understood either way. The second is that ReVo's own remark prefers a plain phrase to either noun: elparolmaniero, manner of speaking, qualified as speciala, landa or fremda. That is dictionary advice rather than usage, but it tells you the noun is felt to be a slightly bookish import.

In Esperanto, the accent is not the problem it is in English. The language was designed so that no accent is the standard one, and the sound lab exists precisely because a Japanese akĉento and a Brazilian one are both correct Esperanto. Senakĉenta speech is not a goal anybody has; being understood is.