Differences with E.S.R.'s proposal
It is obvious that E.S.R.'s final specification is somewhat different than mine. This is due to several reasons, all explained below together with consequences.
The main drift comes from the fact that the sought for a Tengwar-to-Lojban mapping was studied with different issues in mind. Moreover, it seems that our documentation sources on the Tengwar differ, and allowed me to take more facts about them into account (especially on the use of Series III and IV). By a more complete preliminary presentation of the Tengwar system itself, I especially allowed for the different choices made later on to be more obvious.
Additionnaly, I did not try to care about the comfort of a English speaking writer, because this is irrelevant when dealing about what seems to me a core part of Lojban; I thus based my choices rather logically starting from what was already done in other Tengwar modes rather than with a fanciful approach.
Finally, I didn't feel necessary to raise the issue of whether consonant clusters should be represented with single tengwa or not. While it may seem interesting to the casual English speaking writer, there are not enough Tengwar representations of consonant clusters for the all of them, and choosing consonant grouping for some and not for others is, in my opinion, a flawed choice which leads somewhat to cultural bias, and thus do not even deserve to be considered.
In addition to the approach drift presented before, and because while I tried to follow the main direction line than E.S.R. I also tried to figure out the results independently from his work, we ended up with (hopefully) very similar results but not identical.
Choosing the consonants
Firstly, due to the more detailed description of the Tengwar system, I did not face issues with Tolkien's "c" and "k".
Secondly, I left the choice of using the trilled or untrilled forms of "r" to the writer. Lojban and Tengwar allow for both, it would not be sensible to restrict the choice to one or another just because they resemble Latin more.
Thirdly, due to a severe misunderstanding of Tolkien's explanations about "ch" (hey Eric, Tolkien did mean to describe an unvoiced velar spirant with "ch"!), E.S.R faced problems when choosing the tengwa for "x", while it was straightforward for me.
Also, E.S.R. states that the attributes "spirant" and "fricative" stand for the same property of consonants. This is untrue, and this being untrue explains why the fricative "s" and "z" are exiled from the Tengwar table. I did not feel like bothering on how to fetch tengwar for "s" and "z" from the base consonant table, because Grade 3 and 4 are definately for spirants, not fricatives.
And in the very hypothesis that "s" or "z" should be fetched from the base table (on which I disagree, but let's go on anyway), using Series I for "s" is a blantantly wrong choice. "s" is a palato-dental fricative, and not a dental. Grade 3, Series I definately stand for the English-like unvoiced "th", and merging it conceptually with "s" is merely nothing else than bad pronounciation. The same applies for "z": using Grade 4 is also wrong because Grade 4, Series I stands for a voiced "th" (noted "dh" by Tolkien in the Appendix), and not for a palato-dental "z".
This last point is important. The problem is that Lojban's "c" and "j" are the spirant "equivalents" of "s" and "z", which are fricatives. Due to the very structure of the Tengwar table, any attempt to merge conceptually spirants and fricatives leads to wrong choices. One may argue that Lojban does allow for "s" and "z" to be pronounced as dental, but on another hand tengwar nr. 29 and 31 (silme and áze) are known to be widely used for the official pronounciation of the Lojban sounds, and there is no real reason why we should not use them (after all, it is why they were invented at first).
Choosing the vowels
The first drift appears in the understanding of the mode of Beleriand. While E.S.R. understands tengwa hyarmen (nr. 33) to be the representation for "e", I rather think that tengwa yanta (nr. 35) is what was used instead (see by yourself), and all my documentation thinks in the same way.
Also, I have come to make different choices for
what is used in the mode of Beleriand, as E.S.R. did, but not at all for
the same reasons. In particular, E.S.R. considerations on how resemblant
tengwa nr. 36 is to Latin "o", in addition to the fact that the
Sindarin language used by the Elves of Beleriand have a different
pronounciation for "u" than the one used for Lojban, makes his
choice completely fanciful, and even inappropriate given the
usefulness of the digit tengwar.
Finally, different considerations on whether vowels should be written as tehtar or not, and how to rule the writing of vowels led us to different rules on how to use the tehtar.
While our choices are different on some points, I am quite confident that mine are more sensible in many aspects, because I tried to follow the logic of Tengwar instead of a case-per-case study. I also think that E.S.R.'s study lacks many justifications, which I attempted to provide through the prior Tengwar description and following balanced decisions.
I do not state that my choices are not flawed at all. However, hopefully there should not be any conceptual errors, and any real mistake on the choice of tengwar, if any exists, should only be have been caused by inattention. Moreover, given the usefulness of the consequences of choosing this mode rather than another clearly demonstrates its healthy state.
 consonants are said "fricatives" when air is breathed with force in the corresponding position of the mouth, usually because the passage of air is restricted (as with "s"); on the other hand, consonants are "spirants" when air flows smoothly (like in the arabic spirant "h").