Both are fine. The difference is in how the speaker is choosing to frame the event in time.
The goal that France have been looking for is choosing to treat this as an event extending to the present. The goal that France were looking for is choosing to treat it as an event in the past.
Both are grammatical and idiomatic. In this case there is very little difference in meaning.
The people who tell you that it depends on the objective question of when the event or situation finished, are giving you a simplified explanation to try and make it easier to understand; but their description does not match the way that English is actually used.
Many choices in the compound tenses of English (eg the choice of past vs. present perfect, past vs. past perfect, past vs past continuous, perfect vs. perfect continuous, past vs. perfect continuous, simple present vs. present continuous vs. future) do not correspond to objective differences, but to how the speaker is choosing to construct the temporal relationships between events, and often a different choice would be equally appropriate.