In an idle moment I tried to convert my translation (below) into a form 
satisfying the metrical requirements of the original (that is, the 
'rannaigecht' metre known as 'dechnad mór').

"He seven brutal battles bore
right to the rattled lords
in the one day - a thing of awe -
including Crinna’s ford."

The first thing to note is that this fails in a major requirement: each 
line ought to end in a disyllable. But the other requirements are pretty 
much satisfied:
(1) line (b) rhymes with line (d);
(2) line (a) and (c) make half-rhyme with each-other and with (b)&(d);
(3) there is alliteration between two of the stressed syllables in each 
line; and
(4) there is an internal rhyme in (a)/(b) and (c)/(d).

As to (4), I acknowledge that 'thing of' and 'Crinna' is pretty weak.

You will note that I have substituted the requirements of English rhyme 
and half-rhyme for those of Irish rhyme and consonance.

A better effort would do at least one of the following:
(a) meet the requirement for final disyllables;
(b) keep even closer to the meaning of the original ('rattled' in line b 
isn't in the original); or
(c) not read so much like doggerel.

Neil McLeod wrote:
>  >> Lec
>  >> coro bris .uii. catha conna
>  >> forsna flatha finda
>  >> i n-aenlo co n-ô[     ]na
>  >> im chath chrôda chrinda
> Reading line (c) as 'i n-aenlo co n-ó[ga lonn]a', I get:
> "So that he broke seven brutal battles
> upon the fair lords
> in a single day with [fierce perfection]*
> including the bloody battle of Crinna."