You can also change the justification of text by with edit_plot. e.g.

g <- edit_plot(g, col = 4, 
           which = "text",
           # gp = gpar(),
           # Align texts to center
           hjust = unit(0.5, "npc"),
           x = unit(0.5, "npc"))

see here: https://cran.r-project.org/web/packages/forestploter/vignettes/forestploter-post.html for more details.

Hope it helps.