On the fitness of abjads

[Tropylium]

...I strongly doubt that that is true of Latin or most other PIE derivatives, regardless of its truth for PIE.

Yet it's been used for PIE derivatives, cf. Persian and Urdu (and relatives).

I get the feeling that this only works because (1) long vowels are written; (2) Persian is one of the IE languages with the highest proportion of long vowels around (well, Middle Persian anyway; arguably they're all primarily qualitative contrasts today); (3) short /i u/ are proportionally rareish, so writing these and /a/ all as zero doesn't lead to that much contrastive unloading.

[kodé]

Ok, so now I feel stupid for not thinking about this before: why not try writing a Yokutsan language in an abjad? After all, they're the closest thing to a consonantal root language outside Semitic: most roots are two or three consonants + one of four vowel phonemes + prosodic shape. Suffixes are almost all completely distinguishable by their consonants. You'd only need 4, possibly 3 matres lectiones, and only root vowels and/or long vowels need be marked, since most short vowels and suffix vowels aren't necessary for intelligibility. There's not much information on the Wikipedia article, unfortunately: https://en.wikipedia.org/wiki/Valley_Yokuts.

Gotta get to work on this...

[Frislander]

I personally think Salishan (particularly Coast Salish) is a much better candidate, because while they don't use the same kind of templatic morphology, they are famously consonant heavy, and a lot of their morphology does involve some vowel shifts due to stress movement. Here's some Saanich in a modified version of its native orthography as an example (taken from Timothy Montler's Grammar of Saanich, Section 3):

MQ ȻĆYL, ,Y W, QW,Y,Ȼ TS SPHL,. ṈN, TS ṈNṈN,s TSW,NȽ SPHL,. QQY,. QQY, ,L, ,W,N, STṈ S,YȽNs. NȾ, SȻĆL ,Y, ,X̱YTS , TS SNW̱Ƚ TS MNS. ,X̱YTs TS SNW̱Ƚ TS MNs ,Y, ȻȽ ŦYL,Ć , TS SKHLȽ.

[mèþru]

Salishan could probably work IMO.