Is it appropriate to light candles in front of the saint statues while they are covered during Lent?
Although there aren’t any formal Church prohibitions against such a practice, there could be a very practical one—namely, preventing the start of a fire.
Lighting candles before sacred images that the faithful use as a means to focus their prayer on the saint whom they are petitioning is indeed a long and venerable practice in the Church. Meanwhile, the Holy See has allowed for the traditional covering of sacred images during Lent:
In the diocese of the United States, the practice of covering crosses and images throughout the church from this Sunday may be observed. Crosses remain covered until the end of the celebration of the Lord’s Passion on Good Friday, but images remain covered until the beginning of the Easter Vigil (Roman Missal, introduction to the Fifth Sunday of Lent).
There is no formal prohibition against lighting candles before covered images in the Church’s General Instruction of the Roman Missal (GIRM)—see GIRM 318 regarding sacred images. The Church’s Directory on Popular Piety and the Liturgy also contains no such prohibition.
However, given the typical proximity of church statutes to accompanying votive candles, as well as the typical flammability of the Lenten coverings on such images, lighting votive candles in front of them could pose a fire hazard. Stone or plaster statues aren’t flammable, but the material used for covering them during Lent typically is.
Consequently, unless the material of the coverings is clearly fire retardant, it’s best not to cover such images during Lent when the images have accompanying votive candles. Better to forego the coverings than to remove the votive candles. And if coverings are used, then pastors should make sure the votive candles are removed, unless the candles are a safe distance from the statues. Consulting the local fire department would be prudent in such cases.