After seeing "How the scores are calculated in the PLS" (in particular the scores for the first term), now I follow with "How the loadings are calculated in the PLS?" (and in particular the first loading.
Loadings are calculated as regressions of T on every column of X, so in this case we regress "t1_pls" (calculated on "How the scores are calculated in the PLS?") on X, and we do it in a matrix way and we scale it dividing by t(t1_pls)*t1_pls which is an scalar.
Xt.t1_pls<-t(X_msc_centered[odd,]) %*% t1_pls
Now we can plot the reconstructed one with this code and the first loading we get from the "plsr" function of the pls package.
we get TRUE for all the values.