The set of names in the first line is an agglomeration of experimental forms for what should later become Amon Lhaw and Amon Hen ’Hills of Hearing and of Sight’ (LotRII ch.9), but it was originally intended as one place. Apparently Tolkien toyed with the following elements:
tir (see TIR- ’watch, guard’), lenited dir
lhaw ’ears (of one person)’ (LAS2- ’listen’), lenited law (cf. S. lhaw < slasū < SLAS- ’ear’ (PE17:77))
las(t) *’hearing’, cf. Q. lasta ’listen’, lasta ’listening, hearing’ (ibid.)
hen(d) ’eye’ (KHEN-D-E- ’eye’, N. henn > hên)
He arranged them differently looking for the most suitable solution. All forms may all be easily translated:
Most interesting in this example is the spelling ll for unvoiced l according to Welsh orthography; compare the late note on mallorn, which initiated some controversy among scholars: […] in The Lord of the Rings ll is used in the manner of modern Welsh for the medial voiceless l; as in mallorn < malhorn < malþorn < malt ’gold’ and orn ’tree’ (VT42:27)
In this context it should be noted that Tolkien explicitely mentions ’medial voiceless l’, surely being aware having used the spelling Lhaw instead of Llaw. But the appearance of Llaw in the early drafts may be a hint at the fact that the note from VT42 is not a reinterpretation – ll for voiceless lh was perhaps planned at the outset, although it is not mentioned in the appendix .
Amon ’hill’ (AM2-) and Tirlaw *’sight-hearing’
Lasthen *’hearing-eye’ – interestingly not *Lhasthen; a further example of changing Noldorin phonology
Henlas, Hendlas ’eye-hearing’ – the first from drops medial -d- in the -ndl- cluster; both simplify final -st to -s
Finally, Tirmindon and Larmindon are apparently Quenya versions of Amon Hen and Amon Lhaw with tir- + mindon ’tower’ (Silm.index) and las- + mindon (rhotacism s > r).