Is current Gothic normalised transliteration correct or not?

I know that following Gothic and Proto-Slavic (Russian) words are cognate

hairto *sьrdьce сердце
haims *sěmьja семья
taihun *desętь десять
saihs *šestь шесть
staiga *stьdza стезя
hails *cělъ целый
taihswa  *desnъ десница
swaihra *svekrъ свекр
þai те
þaim  *těmъ тем
sai се
?hairda *čerda чреда (череда, очередь)
wairþan вертеть (вращать)
gatairan драть
hailjan (ис)целять
air рано

haurn *sьrna серна
kaurno *zьrno зерно
þaurnus *tь̀rnъ терние

ik аз
ahtau восемь
hund сто

As you can see we get a distinction between Gothic and Proto-Slavic (Russian) when we have "rn" in a steam.
Instead of standart Gothic diphthong "ai" we have "au".

The normalised transliteration (devised by Jacob Grimm) of "au"diphthong before /r/ is /u/,

but I think that

normalised transliteration of Gothic "au" before /r/ is /u/,

but before /rn/ is /ɔː/ as before vowels

Later if I can I will try to justify this proposition.