"My mother was a good artist."
Translation:Mia patrino estis bona artisto.
the sentence alone doesn't imply that, no.
it means that we are talking about a time in the past, and it is pertinent that at that time that the mother was a good artist. it doesn't even imply that she is no longer good at art; with more context, we could infer those things, but this simple sentence doesn't include that.
(I feel that this is a long-winded answer, but if one's native language has a different time system, this might need clarifying. I find myself fretting over whether I should translate things like "ŝi kuras" as "she runs" or "she is running" or even "she does run" because those differences matter in English - even though there's no way I could know from a simple sentence)
((also I think my justification was longer than my answer))