RJU
RJU is used twice in combination with FÉLO (many) and will be short for RJUCHT, in this case meaning 'very'.
Recht viel is still used in German and recht for very is known at least from Middle Dutch (13th century, Maerlant's Rime Bible): die matusael die wan lamech dat was een recht quaet man ('a very evil man' gtb sub 5)
fragments
[055] RJU FÉLO STJURAR ÀND LANDWÉRAR THAM THISSE KÉR NAVT NE SINDE. BRÛDON STOLKES HINNE
[061] A BRITTANJA WÉRON RJU FÉLO MANNA THA LITH WIVA.