Question regarding the translation & tense

Wondering if someone could assist me with how you end up with 'echuidathar' for the translation of 'shall spring' in The Riddle of Strider? In my Sindarin dictionary I found 'echui' for 'awakening', and then hypothesized that adding the element 'tha' creates the future tense, but am unsure as to where the 'da' comes from?

I think the tenses in 'shall be woken' have thrown me also, as it seems to have a future and past tense combined, but I'm no linguist so there's probably a word to describe exactly this!

And also wondering, if the element 'tha' is added for 'he/she/it' but 'thar' is added for 'they'...why does 'the fire', which is the noun in this sentence fit into the category of 'they' as a plural rather than 'it', when 'a fire' implies a singular noun?

Hope this makes sense and thanks so much in advance!

Oops I mean glaegal od i dhúaith tuiatha or glae od i dhúaith tuiatha

Wrong mutation used here.

You want shadows in plural, so dúaith. The plural definite article is in and causes nasal mutation, so "the shadows" would be i núaith.

Ahh okay, I think I was looking at the soft mutation rule for 'd' rather than the nasal mutation rule...thanks so much!