How to left-justify legend text in leaflet with reactive rasters?

Question

I’ve created a shiny app with raster layers plotted over a leaflet map. The user selects which raster to show with two drop down menus: one to select the type of data (mean or SD) the other to select a particular threshold (e.g., mean with 50-deg threshold, mean with 100-deg threshold). I’m having problems with the alignment of labels in the legend. The labels are right justified (see image), but I would like all the labels to be left justified.

Legend with incorrect formatting:

This answer that was just posted to a previous question works perfectly if I dont't have reactive rasters. However, when I try the same thing in code used to display reactive rasters nothing happens. Will this work if I'm using leafletProxy()with clearControls()? Here's the relevant bits of my code, including the shiny server object:

# Load file that lists summary statistics and thresholds
params <- read.csv("parameters.csv")

# Load RasterBrick and name layers
all_rast <- brick("mean-sd-brick.tif")
lyr_names <- paste0(tolower(params$summary), "_", params$threshold)
names(all_rast) <- lyr_names

# Modify function used to format legend labels to include dates when needed 
myLabelFormat <- function(..., dates = FALSE){ 
  if (dates) { 
    function(type = "numeric", cuts) { 
      dd <- parse_date_time(paste("2019", cuts), orders = "%Y %j")
      dd <- format(dd, "%d %B")
      paste0(cuts, " (", dd, ")")
    } 
  } else {
    labelFormat(...)
  }
}

server <- shinyServer(function(input, output) {
  
  reacRaster <- reactive({all_rast[[paste0(tolower(input$summary), 
                                           "_", input$threshold)]]})
  
  legend_title <- reactive({ifelse(input$summary == "SD",
                                   "SD (days)", "Day of year")})
  
  legend_labels <- reactive({ifelse(input$summary == "SD",
                                    myLabelFormat(dates = FALSE),
                                    myLabelFormat(dates = TRUE))})
  
  output$map <- renderLeaflet({
    leaflet() %>%
      fitBounds(lng1 = -88, lat1 = 35, lng2 = -65, lat2 = 47) %>%
      addTiles()
  })
  
  observe({
    pal <- colorNumeric(palette = "viridis", 
                        domain = values(reacRaster()),
                        na.color = "transparent",
                        reverse = TRUE)
    
    leafletProxy("map") %>%
      clearImages() %>%
      clearControls() %>%
      addRasterImage(reacRaster(), 
                     colors = pal, 
                     group = "Value",
                     layerId = "Value",
                     opacity = input$opacity, 
                     project = FALSE) %>%
      addLegend("bottomright", 
                pal = pal, 
                values = values(reacRaster()),
                labFormat = legend_labels(),
                title = legend_title(), 
                opacity = 0.8) %>%
      htmlwidgets::onRender("
        function(el, x) {
          var labels = el.querySelectorAll('.info.legend text'); // 1
          labels.forEach(function(label) {
            label.setAttribute('text-anchor', 'start'); // 2
            label.setAttribute('dx', '5'); // set left indentation [px]
          });
        }
      ") %>%
      addImageQuery(reacRaster(),
                    digits = 2,
                    type = "click",
                    position = "bottomleft",
                    prefix = "",
                    layerId = "Value",
                    project = TRUE)   

  }) # end observe
}) # end server