Anyway, if the canon way of expressing the intended meaning is {tu'lu'be'}, then I'm ok with it. But is it canon indeed ?

First off, both tu'be'lu' and tu'lu'be' are canon.

SuvwI'pu' qan tu'lu'be'.
There are no old warriors. (TKW)

QuvlIjDaq yIH tu'be'lu'jaj
May your coordinates be free of tribbles. (PK)

Next, canon supports the idea that rovers do not necessarily only affect the immediately preceding element. While this is true sometimes (e.g., the choHoHvIp examples in TKD) it is not true always. For instance:

nom yIghoSqu'
Maximum speed! (ST5)
-qu' is intensifying the entire sentence, not just the verb.

Hoch DaSopbe'chugh batlh bIHeghbe'
Eat everything or you will die without honor.
-be' is negating the entire main clause, not just the verb.

Finally, as Lieven says, tu'lu' appears to be a somewhat fixed phrase that doesn't always work as a standard basic sentence. Although tu' means discover, tu'lu' is often used where no discovery occurs; it merely signifies a thing's presence. In this sense it may be considered an idiom whose formula you simply follow.

-- 
SuStel
http://trimboli.name