以下“已解决代码”解决了该问题。OP代码的一些变更在下面进行了注解，总结如下：
1.在server()节中插入outputOptions(output, 'hottable2', suspendWhenHidden = FALSE)，以便更新位于单独选项卡面板中的第2个表，而操作按钮从另一个选项卡面板驱动该表;允许React性立即跨越未被查看的选项卡面板
1.即使有了上面的修正，“hottable 2”表也必须点击才能完全渲染。R whiz Stéphane Laurent指出，当以这种方式重新渲染时，Shiny中存在一个已知的bug，他的html解决方案相应地包含在下面server()部分中用于“hottable 2”的rhandsontable()函数的修订代码中并进行了注解
解析代码：

library(dplyr)
library(rhandsontable)
library(shiny)

myDF1 <- data.frame('Series 1' = c(1,24,0), check.names = FALSE)
  rownames(myDF1) <- c('Term A','Term B','Term C') 
myDF2 <- data.frame('Series 1' = c(20,15), check.names = FALSE)
  rownames(myDF2) <- c('Boy','Girl') 

ui <- pageWithSidebar(
  headerPanel(""),sidebarPanel(""),
  mainPanel(
    tabsetPanel(
      tabPanel("Master table", hr(),
        rHandsontableOutput('hottable1'),br(),
        actionButton("addSeries", "Add", width = 80),
        fluidRow(
          column(2,actionButton("delSeries","Delete", width = 80)),
          column(3,uiOutput("delSeries2")) 
        ),
      ),
      tabPanel("Slave table", hr(),rHandsontableOutput('hottable2'))
    )
  )
)

server <- function(input, output) {
  emptyTbl1 <- reactiveVal(myDF1)
  emptyTbl2 <- reactiveVal(myDF2)
  
  observeEvent(input$hottable1, {emptyTbl1(hot_to_r(input$hottable1))})
  observeEvent(input$hottable2, {emptyTbl2(hot_to_r(input$hottable2))})
  
  output$hottable1 <- renderRHandsontable({
    rhandsontable(emptyTbl1(),rowHeaderWidth = 100, useTypes = TRUE)%>%
      hot_context_menu(allowRowEdit = FALSE, allowColEdit = FALSE) %>%
      hot_cols(colWidths = 80)
  })
  
  output$hottable2 <- renderRHandsontable({
    rhandsontable(emptyTbl2(),rowHeaderWidth = 100, width = 800, height = 450,useTypes = TRUE)%>%
      hot_context_menu(allowRowEdit = FALSE, allowColEdit = FALSE) %>%
      hot_cols(colWidths = 80) %>%
      # next section of html addresses issue of correcltly rendering the slave table:
      htmlwidgets::onRender(
        "function(el, x){
        var hot = this.hot;
        $('a[data-value=\"Slave table\"').on('click', function(){
          setTimeout(function(){ hot.render(); }, 200);
        }); 
      }"
      )
  })
  
  observeEvent(input$addSeries, {
    newCol1 <- data.frame(c(1,24,0))
    newCol2 <- data.frame(c(20,15))
    names(newCol1) <- paste("Series", ncol(hot_to_r(input$hottable1)) + 1)
    names(newCol2) <- paste("Series", ncol(hot_to_r(input$hottable2)) + 1)
    emptyTbl1(cbind(emptyTbl1(), newCol1))
    emptyTbl2(cbind(emptyTbl2(), newCol2))
  })
  
  observeEvent(input$delSeries3, {
    tmp1 <- emptyTbl1()                                     
    tmp2 <- emptyTbl2()                                       
    if(ncol(tmp1) > 1){
      delCol <- input$delSeries3                              
      tmp1 <- tmp1[ , !(names(tmp1) %in% delCol), drop = FALSE]  
      tmp2 <- tmp2[ , !(names(tmp2) %in% delCol), drop = FALSE]  
      newNames <- sprintf("Series %d",seq(1:ncol(tmp1)))       
      names(tmp1) <- newNames                                  
      names(tmp2) <- newNames                                  
      emptyTbl1(tmp1)                                         
      emptyTbl2(tmp2)   
    }
  })
  
  output$delSeries2 <- 
    renderUI(
      selectInput("delSeries3", 
                  label = NULL,
                  choices = colnames(hot_to_r(input$hottable1)), 
                  selected = "", width = '100px',
                  multiple = TRUE)
      )
  
  outputOptions(output, 'hottable2', suspendWhenHidden = FALSE) # this updates slave panel even when hidden
  
}

shinyApp(ui,server)