Name Changes?

[Maédhros]

Regarding Orodreth/Artaresto/Artaher. It seems that the correct sindarized named of Artaher is Arothir, instead of the Rodreth - Orodreth name.
But does that mean necessarily that [Orodreth] would use the correct sindarized name Arothir? Lets suppose for a moment that we should use Arothir for the name of [Orodreth]. How then can we explain the use of the name Orodreth from the Ruling Stewards of Gondor?
From The Lord of the Rings: Appendix A

Hallas 2605, Húrin II 2628, Belecthor I 2655, Orodreth 2685, Ecthelion I 2698, Egalmoth 2743, Beren 2763, Beregond 2811, Belecthor II 2872, Thorondir 2882, Túrin II 2914, Turgon 2953, Ecthelion II 2984, Denethor II. He was the last of the Ruling Stewards, and was followed by his second son Faramir, Lord of Emyn Arnen, Steward to King Elessar, F.A. 82.